@@TommyBo42 Not "but it approaches infinity". Instead, "something" approaches infinity. That something is actually "something else" ppl dont understand unless they have knowledge of math analysis.
@@TommyBo42 no if f(x)=1/x .. as x increases or approaches infinity f(x) gets smaller ..if x goes towads zero f(x) increases .. but f(x)is Undefined for x=0 ..it makes as much sense as take the Inverse sine of 2 wich is undefined
I thought about it like this. At the beginning there is one right-handed person in the room. How many left-handed people do I need for there to be 2% right-handed people in the room? Clearly I need 49. Therefore I have to remove 50 left-handed people. I did all this in about 5 seconds.
yeah, it's easiest and fastest to turn the percentage of right-handed people into a ratio to all people in the room. I thought about it about the same: 1% is 1:100, and then 2% is 2:100, or 1:50. to get from 1:100 to 1:50, you take away 50 left-handed people.
I'm glad to see that a lot of people didn't go through the entire process, and rather know or have come to the conclusion that in order to double the percentage of right-handed people, you need to halve the total number.
Hello. I've only began to pursue math recently after a long break since the end of school. This problem did not come intuitively at all for me, do you have anything you would recommend beside doing more of these, or is it just a natural talent I don't have?
@@TroySturges-g6u make excel spreadsheets about video games with respect to crit chance, crit damage, attack speed, damage mitigation, effective total health etc. You'll get intuitive about percentages real quick
That is going through the entire process, only very quickly. When you solve in your head, you go through all the steps, just without spending so much time writing.
That is a superb analysis from you there. The quiz show that this question is from i was watching when aired, i was furious that i got it wrong, but your lesson there im gunna remember for future maths questions.
I realized immediately that just removing a person would result in a non-integer percentage, but it took me a while to realize what else to do. But I'm proud to say I got the answer before he said it!!!
ya, took a min realise what was asked... but its easier calculate on those right handed u want right handed to be 2% ot the total left in the room -> 1/.02=50 ppl must be left in the room ..would had been fun if thay asked how many have to leave to bring it down to 97%
I thought about it like this: When you want 100 people with 98% left handed, you need 98 left handed and 2 right handed people. Then I divided both by two so there’s only one right handed person. That left me with 49 left handed people. And 99-49=50, so 50 left handed people have to leave.
@@TrentRProductions Lol, I was reading the comments while assuming the video gave the quick solution. But now I took a look at the video and it is truly horrible, lol.
I calculated it using some algebra. The original percentage of 99% is 99 left-handed people out of 100 people in total. If we represent the number of left-handed people that will leave the room with “x”, then we have (99 - x)/(100 - x) = 98% (the new percentage we are looking for) = 0.98. Once you work it out, you get x = 50.
@@ronald3836now tell me how many people need to leave for the percentage to be below 93.5%. You can’t do that just by looking at it but the formula still holds up. Maybe think for a second why what he is doing might be important
@@JuergenW. the concept of the original show is the questions get harder based on how many people are able to answer them, and the final question is supposed to be answerable only by 1% of people. They have a panel of 100 people answering the questions along with the contestant and you see how many of them go out on each question. Of course, it doesn't mean the same 1% will be able to answer all of the 1% questions on the show. Some, like this one, I find quite easy. Others are more complicated.
This is the first one on your videos that I figured out immediately. My brain went to one person is 1% in the initial scenario, so for someone to be 2% of the group there would need to be half the total people.
Took me ages to realize if people leave there would no longer be 100 people... Once this was clear, answer became obvious. In a TV show I would have panicked.
The Percentile quantities were Supposed to Confuse the Reader, as some commenters STATED, it's Best to make a Formal Computation rather than Follow a Seemingly Logical answer...😊😎👍
I'm glad I'm not as dumb as I thought 😅. I got it fairly quick. 1% = 1 99%= 99 Cross multiplication: 2% = 1 98% =? (1 X 98)/2 = 49 Keep 49 out of the 99, so we kick out 50.
Go in the opposite direction: start with 1 right-handed person. How many lefties do you need to bring in to the room to get to a ratio of 100:2 (given that the max number of righties is 1)?
I used my own method, my 26 years of experience of math, my very own logic and solve it by only 5 seconds by just jumping the video at the end and got 50 as an answer
As others have pointed out, I solved it by thinking how many people in total they had to be for one person to equal 2%, which is one out of fifty (so 49 others). Thus simply 99-50 = 49. But I appreciate the more algebraic solution to the general problem, where the numbers might be harder to think about in your head.
Quick intuitive approach - equation balancing, you want to double the number of right handed people, inversely, you need to half the number of left handed.
You need to halve the total number of people in the room! Your stated approach 99/2=49.5 is a bit brutal and doesn't solve the problem! ( Not questioning your reasoning, you didn't word it right! )
@alexandergutfeldt1144 correct, I didn't want to write an essay. I left out the parts of keeping the total number of people at 100 by converting the lefts to rights, reducing by the desired ratio (accidental time stamp), then converting back with the new group. Thanks for keeping me honest, I lazy math often.
@@alexandergutfeldt1144 are you stoo-pid ?? He clearly wrote "quick INTUITIVE approach" He didn't write "correct calculation" Do you ever get invited to social events?
I used a slightly different method. 99 are left handed so that means 1 is right handed. 1 out of 100 equals 1% 1 out of 50 total equals 2%. That means 50 less Total people.
@@utopiandystopia1383 you do realize that ChatGPT and AI are not the same thing, right. ChatGPT is just one instance of general knowledge AI that is more of a gimmick to introduce AI to layman society and make hype for it than a really functional AI. We already have loads of much better AI models for specialized tasks. I would love to see a game with fully AI based npc responses. For people that don't have many friends or just have hard time to gather them at the same place and the same time, it would as close as they can get to a true RPG session 😁
apparently I'm the only person who thought this was a rounding problem and said 35 people need to leave, because 65/66 = 0.984 which rounds down to 98%
Because it's not a rounding problem and you can have percentages with decimal places in them, such as 98.4% with no requirement to round them into a whole number. By assuming that you should round the percentages, you are essentially making up your own question rather than solving the question that was actually asked.
I’m so glad you’ve put this because I thought I was gonna be the only one. The question didn’t specify EXACTLY 98% so suggesting rounding it is perfectly valid imo.
By assuming you *can’t* round them is also making up that rule. The numbers they’ve given are rounded, otherwise they could have been written as 99.00% 👀🤷♂️😂
Another problem is asking how to bring the percentage down to 96%. The answer is 75 left-handed people must leave the room leaving 1 right-handed person and 24 left-handed people. 24 out of 25 is 96%. The easier way to calculate this is to concentrate on the number of right-handed persons which is always one. 1=4x/100 which equals 25 so there are 24 left-handed and 1 right-handed so 75 of 99 left-handed must leave the room. In the problem given the equation would be 1=2x/100 which equals 50 so there is 1 right-handed and 49 left-handed (49 out of 50 is 98%) so 50 left-handed must leave the room. This math is easier than what is shown.
50 people, 99/100 is 99% 49/50 is 98% Kevin of Vsauce2 covered this exact thing albeit with a different premise (something to do with potatoes iirc). You can also look at it the other way round, there is 1 right handed person 1 out of 100 is 1% you need it to be 2% so 1/0.02 (or 100/2) which is 1 out of 50
04:47 It would be easier to calculate this, if we would firstly multiply both sides by 100 (to get 100=2*x), and secondly divide both sides by 2 (to get 100/2 = x and x=50).
I read the thumbnail and immediately started guessing n/(n+1) values until I found the answer, then I started the video. The algebraic method and logic makes a lot of sense!
I solved it mentally with algebra. The hardest part was remembering the numbers, keeping them in mind. Here ‘s the equation: 99-x/ 100-x = 98/100. It took me more than 30 seconds to do it, though. Still, not bad for an octogenarian!
Easier mathematical manipulation if you recast as right-handed percentage. 1 right-handed person in the room with 99 left-handed is 99% left handed or 1% right handed. So to go down to 98%-left is to go up to 2%-right. Equation is almost the same but much quicker to solve since there is always 1 right handed peron and "x" left-handed people need to leave ther room 1/(100-x) = 0.02 Note it is easier if you recall that 0.02 = 2/100 = 1/50 1/(100-x) = 1/50 So 100-x = 50. x=50
I am sorry..I zoned out halfway through the proces and thought about if I could get the football court in recess before the other classes... just like 27 years ago when I was in math class....
to try to solve it within 30 seconds a viable option is 98% = 98/100 reduce this fraction 49/50 luckily the original condition was 99/100 = 99% so removing 50 from numerator and denominator (removing 50 left handed people removes 50 from total) leads to 98% looking at the comments, the 1% to 2% trick is even better (thinking of the complement, amount of right handed people) 1/100 2/100 = 1/50 (so removing 50 from 100) either way, final ans 50.
I told my pal about this after it aired and he said its fairly basic maths and solved it in under 2 minutes. I had no idea but after it was explained to me it made perfect sense
Very nice demonstration. I went the other way. The number of rightanded is constant, always 1. If 98% are lefthanded then 2% are right handed. The total number of people to have 1 person be 2% is 2/100=1/x -> 2=100/x -> 2x=100 -> x=50. W started with 100 people, so (100-50) = 50 has to leave.
I still haven't watched the video nor read the comments, this is how I did it: 98% = (99-x)/(100-x), which yields x = 50. My explanation for the equation is the following. "99-x" is the final number of left-handed people in the room, x is the number of lefties who left (pun intended. Laugh!). The denominator will simply be the total number of of people in the room, which is one more than "99-x", so "100-x". Now, simply equals that with 98% and solve for x. By the way, the addition of one more comes about because there is a right-handed, airhead strolling about this weird left-handed people congress. Edit: yep! 👍🏻
In order for ONE right handed person to represent 2% of the total they have to be the only one out of 50 1/50 = 0.02 = 2%. One for every 50 equals two for every hundred in percentgage terms that means the room has to lose a total of 50 left-handed people.
Like I mean if the question went Like this In a room of 100 people, 99% are left-handed. How many left-handed people have to leave the room to bring that percentage down to 97%?
@@kingellsgaming Not without cutting people in pieces. 3/100 equals 1 out of 33 1/3. So impossible 66 2/3 persons leaves the room. I don´t like that so let us take 96% as an new example. 4% rigthhanded is one out of 25. 75 lefthanded have to leave the room. I think you got it.
I actually managed to do this as well after thinking about it for about 5 minutes and here’s my formula for this: x/x+1 * 100 = 98% Where x is the number of people left when there are 98% of people are left handed and the x+1 ensures that there is still one person who isn’t left handed With a bit of algebra you’ll get x = 49 Subtract this from 99 and your answer is 50 👏
My solution is more cogent though. We know that x people has to leave. Then the number of people remained (left-handed) is 99-x. This is 98% of the total people, so we have the equation 99-x=0.98(100-x). When you solve this, you get x = 50, which is the number of left-handed people that has to leave.
50. Basically the single right handed person is 1/100. For it to become 2/100 = 1/50, the number of left handed must decrease to 50-1=49. So from 99 to 49 is 50 left handed people must leave.
An another approach i would like to suggest goes like this: 99-x/100-x=98/100 100(99-x)= 98(100-x) 9900-100x=9800-98x 9900-9800= 100x-98x 100=2x x=100/2 x=50
I'm surprised that I got this right when I was watching the 1% club on ITV. The way I worked it out was, 1 person makes up 2%, therefore there must be 50 people in total in the room.
the easiest way to figure it out is to put the question on the reverse: how many left-handed persons need to leave the room to have the right handed guy representing 2% of the total. and now the answer is evident: 50.
Because we are dealing with strictly whole numbers here, there are only a two ways a group of 100 or less can contain a subgroup comprising EXACTLY 98%. Namely, 98/100 or 49/50. The first is precluded since we start with 99/100 and we can't get to 98/100 by removing. So the second is the only outcome that fills the requirement: the number of lefties must go down by 50, leaving the original righty.
If this were a question from a TV show, the participant likely would not have had enough time to solve the equation as Steve demonstrated. Perhaps we can think of it this way: The percentage calculation in the question is always in the form of (x-1)/x, where x is the total number of people left in the room. The required percentage, 98%, can be expressed as 98/100=49/50, which matches the form (50−1)/50.
I love the video. I recognized the trap from manipulating probabilities and solved it from a different perspective. I watched to see if there was an alternate method and I was genuinely surprised the proof led to the same conclusion and final step.
What’s crazier is in order to get down to 97%, you’d have to remove sixteen and two thirds more left-handers from the room. To get down to 96%, you’d then have to remove eight and a third more left-handers. To decrease by 1% each time, the total people who STAY in the room must go from 100 to 50 to 33.33 to 25 to 20 to 16.66 to 14.285714 etc. Notice this follows the pattern of denominators 1/1, 1/2, 1/3, 1/4, 1/5, 1/6, 1/7 etc. The number of people who need to LEAVE the room goes from 50 to 16.66 to 8.33 to 5 to 3.33 to 2.380952 to 1.7857142 etc. which follows a different pattern of denominators 1/(1x2), 1/(2x3), 1/(3x4), 1/(4x5), 1/(5x6), 1/(6x7) etc.
A simpler way to do this is to think of it from the right hand persons perspective, since the people we remove are only left handed, the 1 right handed person is constant, and therefore the percentage value they hold can help in calculating the rest, 1 is currently 1% of the total number of people, and since we need left handed people to become 98%, the remaining 2 % is the 1 Right handed person. So 1 went from being 1% of 100 to 2% of x. From there, it's straight forward. x*2/100=1. x=100/2=50. so the total number of people remaining in the room is 50, subtract that from the original number and you have the number of people that needs to be removed in order to match the required percentages.
Nice seeing it all done out thoroughly. My thought process just went "if we only have 1 righty, what number is one 2% of? Yep, 50, get rid of 50 lefties".
I know dividing by 0.02 is mathematically correct, but very few people connect the dots and realise its same as multiplying by 50... next time it would be better say: 0.02 if you multiply by 5 you get 0.1 and if you multiply by another 10 you get 1 so lets multiply both sides by 50. Its easier to understand where the number came from OR rewrite it like 2/100 and multiply by its inverse 100/2. I have math as my hobby and while i understand some calculus lvl math I struggle sometimes.. mainly with proofs but also with some complex number problems and with "curve?" integrals (not native english speaker). Thanks for your videos and effort to make more people interested in math.
also you can think of it as 1 person being equal to 1% in the beginning and at the end each person is worth 2% of the total. so you can put it in an equation where the left handed have to equal 98% and the right handed being 2% meaning that there can only be a difference of 1 person between the two groups and the only way to get to 100 this way is with 49 and 50
Originally heard this question with very watery potatoes. (If a potato is 99% water by weight, what percentage of the weight would you need to dehydrate in order to make it 98% water)
I did it that way: In the end, 1 (right-handed person) =2% x (x being the amount left) 50=100% x So 50 people left, from 100 at the start, 50 left then.
I did that 1% is represented as 1/100 (per-cent, as in per every one hundred) and you want 2/100. But you only have one singular right handed person so you have to do 1/50. 100-50 is 50 people. For reference, I am 13 years old and majority of my middle school class got it right. This is a middle school question, but not all adults remember such practice.
For me, the best mental method would be to think of the right handed (1) and put it as a constante, so to have 98% of left handed it means that 2% = 1, 100% = 2*50% => 2*x=98 => x=49 Then u know the total ammount of left handed guy and the original ammount so its easy
I initially thought the answer was 1, but then realised that then goes from 1 right handed in a hundred to 1 in 99 which does not equate to 98%. Then I realised you need one person to be 2% of the room which means there needs to be 50 people, of which one is right handed. So to go from 100 to 50, then 50 must leave.
Funny that my brain figured out "we can't double right hand so it must be halved" almost immediately but justifying it with math took me (not the video) 5 minutes
Similar effect is seen in video games with damage and damage reduction values. 100 damage while having 90% reduction is 10 damage. Getting just 5% more to 95% reduction halves the incoming damage to 5.
Its pretty easy to solve in your head once you stop thinking about left handed people and start thinking of the single right handed person. Not sure if it took me more or less than 30 seconds, but somewhere in that general range.
The first thing to do is just go the brute force route and see what % will be at some nice number that you can easily multiply into 100. Like 50, which just turns out to be the answer. Or you can understand that you have 1% and need 2%, thus you need twice more, which means that you need to divide the total by two without decreasing your 1%, thus you need 50 left-handed people to leave.
50, 1 right handed, to double that, half the people need to leave After finishing the video: There are 2 simpler ways at looking at this problem. 1 & 99, what do we need to do to make 100 people = 98%, we simply replace 1 lefty with a righty, 2 & 98, and now, we can just remove half, 1R and 49L to maintain the ratio, or 50 people. The other way is as above. We want to make 1% become 2%, since we are doubling, we need to halve. I think these concepts are a little more intuitive, and easier to grasp. I wouldn't be surprised if even mathematicians spit out the wrong answer, or had to give it a bit more thought directly because they didn't look at the 1%, and instead focused on the 99%.
Easier way to calculate this: work with the fact that the number of right-handed people in the room (1) must be 2% in the final situation. If y is the total number of people in the room in the final situation, and 1 person equals 2% then y = 50. (1/y = 2% = 2/100 = 1/50 --> y = 50) And the number of left-handed people must be 50 - 1 = 49. So from the original 99 left-handed people, 50 have to leave.
I simply thought that I need to find a fraction where nominator and denominator differ by 1. so I thought of 49/50, which is 98/100, so 100-50=50 people have to leave the room.
1 in a 100 (1+ 99 (%)) must go to 2 in a 100 (2 + 98(%)). But we had only 1 righthanded, so 2 and 98 divided by two (in order to get 1 righthander), leaves 49 lefthanders. We had 99 lefthanders, so 50 have to go...😊
1 ÷ 0 = 0? (a 3rd grade teacher & principal both got it wrong), Reddit r/NoStupidQuestions
ua-cam.com/video/WI_qPBQhJSM/v-deo.html
Undefined, but it approaches infinity. So, 0 is about as wrong an answer as you can get.
@@TommyBo42 Not "but it approaches infinity".
Instead, "something" approaches infinity.
That something is actually "something else" ppl dont understand unless they have knowledge of math analysis.
@@TommyBo42 no
if f(x)=1/x .. as x increases or approaches infinity f(x) gets smaller
..if x goes towads zero f(x) increases
.. but f(x)is Undefined for x=0
..it makes as much sense as take the Inverse sine of 2 wich is undefined
Hence, my answer that it is undefined, but it approaches infinity as x gets closer to zero :) Cheers!
初探討極限理論? 相當嗨~
其實學好一點數學, 也沒什麼.
I thought about it like this. At the beginning there is one right-handed person in the room. How many left-handed people do I need for there to be 2% right-handed people in the room? Clearly I need 49. Therefore I have to remove 50 left-handed people. I did all this in about 5 seconds.
yeah, it's easiest and fastest to turn the percentage of right-handed people into a ratio to all people in the room. I thought about it about the same: 1% is 1:100, and then 2% is 2:100, or 1:50. to get from 1:100 to 1:50, you take away 50 left-handed people.
yeah, this is the obvious way to do it and shows that logic beats algebra in speed
@@eventhorizon853speed is not the reason you use algebra. It’s because of its reliability and verifiability.
Yeah very clickbait
yes
I'm glad to see that a lot of people didn't go through the entire process, and rather know or have come to the conclusion that in order to double the percentage of right-handed people, you need to halve the total number.
Hello. I've only began to pursue math recently after a long break since the end of school. This problem did not come intuitively at all for me, do you have anything you would recommend beside doing more of these, or is it just a natural talent I don't have?
@@TroySturges-g6u make excel spreadsheets about video games with respect to crit chance, crit damage, attack speed, damage mitigation, effective total health etc. You'll get intuitive about percentages real quick
@deesire thank you for your reply, I will give it a go!
That is going through the entire process, only very quickly. When you solve in your head, you go through all the steps, just without spending so much time writing.
Yeah, but if the numbers are awkward, you gotta know the math.
I went in the opposite direction: if 1 right-handed person is 2%, how many people you must have in the room? 50. Great video.
The small change from 99 to 98 obscures the large relative change from 1 to 2. This is a good general lesson.
That is a superb analysis from you there.
The quiz show that this question is from i was watching when aired, i was furious that i got it wrong, but your lesson there im gunna remember for future maths questions.
50 people. That stumped me for a hot minute before i realized what happens when you remove a person.
The bouncer will have had a full day!
I knew it wasn't 1 person but I didn't expect 50 .😂
But 49/50 will get you 98%.
I realized immediately that just removing a person would result in a non-integer percentage, but it took me a while to realize what else to do. But I'm proud to say I got the answer before he said it!!!
ya, took a min realise what was asked...
but its easier calculate on those right handed
u want right handed to be 2% ot the total left in the room ->
1/.02=50 ppl must be left in the room
..would had been fun if thay asked how many have to leave to bring it down to 97%
From memory: _this is one of those where it's about half isn't it?_
I thought about it like this:
When you want 100 people with 98% left handed, you need 98 left handed and 2 right handed people.
Then I divided both by two so there’s only one right handed person. That left me with 49 left handed people.
And 99-49=50, so 50 left handed people have to leave.
Yes! And this is so much easier
@@TrentRProductions Lol, I was reading the comments while assuming the video gave the quick solution. But now I took a look at the video and it is truly horrible, lol.
That's clever
I calculated it using some algebra. The original percentage of 99% is 99 left-handed people out of 100 people in total.
If we represent the number of left-handed people that will leave the room with “x”, then we have (99 - x)/(100 - x) = 98% (the new percentage we are looking for) = 0.98.
Once you work it out, you get x = 50.
@@ronald3836now tell me how many people need to leave for the percentage to be below 93.5%. You can’t do that just by looking at it but the formula still holds up. Maybe think for a second why what he is doing might be important
The multi marker skills are impressive
Yes, I noticed that in another of his videos.
How many markers can he multiplex ...maybe 5 ? :)
he is a true master of the ancient Black Pen Red Pen Technique 🖍️
@@LonkinPork 2 pens, 1 guy
@@Not.Your.Business reminds me of 1 cup 2....
100% This. It's the most impressive part of the explanation. I'm glad we all noticed it and appreciated it together.
Percentage = x/ (x+1), set percentage to 98/100 which is = to 49/50=x/(x+1), x ist equal to 49. So 50 left handed ppl had to leave since 99-50 is 49
I couldnt remember the percentage formulas so couldnt do it in the time alloted, 40 years ago maybe
It feels good to be a part of that 1% club
The club of 1% righthanded people in the room?!?
@@JuergenW. the concept of the original show is the questions get harder based on how many people are able to answer them, and the final question is supposed to be answerable only by 1% of people. They have a panel of 100 people answering the questions along with the contestant and you see how many of them go out on each question.
Of course, it doesn't mean the same 1% will be able to answer all of the 1% questions on the show. Some, like this one, I find quite easy. Others are more complicated.
This is the first one on your videos that I figured out immediately. My brain went to one person is 1% in the initial scenario, so for someone to be 2% of the group there would need to be half the total people.
That's a brilliant way of thinking about it.
Me too. I'm much too lazy to do the math when there is an easier way to come up with the answer.
That’s how I did it as well.
No need to guess. Just reason how many people you need to have the sole right-handed person represent 2%.
2% means 1 out of 50. That's all.
Yup, question only said remove left handed not add right handed
Took me ages to realize if people leave there would no longer be 100 people... Once this was clear, answer became obvious.
In a TV show I would have panicked.
I found it easier leaving the percentage as a fraction:
(99-x)/(100-x) = 98/100
100(99-x) = 98(100-x) (distribute denominators)
9900 - 100x = 9800 - 98x
98x - 100x = 9800 - 9900
-2x = -100
x = 50
don't even need all that. 2% is 1/50th of total. so 50 people need to leave
@@bytemeahyou DO need all that to work it out in a formal and logical fashion that others can follow and learn from. Shortcuts don’t do that.
Man thanks so much
It is much easier 🎉🎉
The Percentile quantities were Supposed to Confuse the Reader, as some commenters STATED, it's Best to make a Formal Computation rather than Follow a Seemingly Logical answer...😊😎👍
Much easier to understand
Thanks for the Christmas gift of allowing us to momentarily feel smart.
I'm glad I'm not as dumb as I thought 😅. I got it fairly quick.
1% = 1
99%= 99
Cross multiplication:
2% = 1
98% =?
(1 X 98)/2 = 49
Keep 49 out of the 99, so we kick out 50.
50. Had to pull out a calculator and guess-and-check. Never would have been able to figure that out on the spot on a gameshow.
Yeah with a lot of money riding on the answer - no pressure!
Had to quickly do it in my head. So, I'm pretty sure I would have got it.
Go in the opposite direction: start with 1 right-handed person. How many lefties do you need to bring in to the room to get to a ratio of 100:2 (given that the max number of righties is 1)?
The gameshow gives you 30 seconds to solve, took me about 15 when I realized 98/99 is still pretty close to 99%... and a short jump to 49/50 is 98%.
I used my own method, my 26 years of experience of math, my very own logic and solve it by only 5 seconds by just jumping the video at the end and got 50 as an answer
In chemistry, if you want to double concentration - you should somehow halve mass or volume. 😉
Same thing indeed.
5:00 fifty!
This assumes you don't remove the one right-handed person! Then, it suddenly becomes (and remains) 100% left-handed.
@@jamesharmon4994
The original problem says ‘how many left-handed people have to leave the room’.
@jamesharmon4994 the questions specifies left handers
Instead of leaving the room just make them ambidextrous and then slowly phase out their left hand
@Kerguelen.Mapping Then... you just have to do it to ONE person.
As others have pointed out, I solved it by thinking how many people in total they had to be for one person to equal 2%, which is one out of fifty (so 49 others). Thus simply 99-50 = 49. But I appreciate the more algebraic solution to the general problem, where the numbers might be harder to think about in your head.
Quick intuitive approach - equation balancing, you want to double the number of right handed people, inversely, you need to half the number of left handed.
You need to halve the total number of people in the room! Your stated approach 99/2=49.5 is a bit brutal and doesn't solve the problem!
( Not questioning your reasoning, you didn't word it right! )
@alexandergutfeldt1144 correct, I didn't want to write an essay. I left out the parts of keeping the total number of people at 100 by converting the lefts to rights, reducing by the desired ratio (accidental time stamp), then converting back with the new group. Thanks for keeping me honest, I lazy math often.
@@alexandergutfeldt1144 are you stoo-pid ??
He clearly wrote "quick INTUITIVE approach"
He didn't write "correct calculation"
Do you ever get invited to social events?
I used a slightly different method.
99 are left handed so that means 1 is right handed. 1 out of 100 equals 1%
1 out of 50 total equals 2%. That means 50 less Total people.
Wow that’s really smart. I feel like that observation is the fastest method possible.
we use the same method what a coincidence
Did you use it before or after you got the answer? 😊
@@davidpereira4455 that's how I got the answer.
Bro how lucky am I to search this and only your video came up that was uploaded 5hr ago. Nice
i just watched 10 times how you switched your pens 1:03 ... awesome! and great content!
Out of interest I asked ChatGPT and it told me the answer was 1, the right-handed person had to leave the room lol
Chat gpt o1 respondeu corretamente.
Thats chat gpt for you, cant even do what computers are supposed to be good at 🤣 i cant belive people want that thing to be npc dialogue for games
I asked chat Gpt and it gave the correct answer with calculations
@@utopiandystopia1383Maybe you are not using Gpt 4o I tried it multiple times and it gave the right answer
@@utopiandystopia1383 you do realize that ChatGPT and AI are not the same thing, right. ChatGPT is just one instance of general knowledge AI that is more of a gimmick to introduce AI to layman society and make hype for it than a really functional AI. We already have loads of much better AI models for specialized tasks. I would love to see a game with fully AI based npc responses. For people that don't have many friends or just have hard time to gather them at the same place and the same time, it would as close as they can get to a true RPG session 😁
apparently I'm the only person who thought this was a rounding problem and said 35 people need to leave, because 65/66 = 0.984 which rounds down to 98%
Because it's not a rounding problem and you can have percentages with decimal places in them, such as 98.4% with no requirement to round them into a whole number. By assuming that you should round the percentages, you are essentially making up your own question rather than solving the question that was actually asked.
I’m so glad you’ve put this because I thought I was gonna be the only one.
The question didn’t specify EXACTLY 98% so suggesting rounding it is perfectly valid imo.
By assuming you *can’t* round them is also making up that rule.
The numbers they’ve given are rounded, otherwise they could have been written as 99.00% 👀🤷♂️😂
50. It’s a simple equation (99-x)/(100-x) = 0.98 . Which simplifies to 0.02x = 1 and hence x=50
This is one of those problems that I'd get right instantly and lose credit for not showing my work
Another problem is asking how to bring the percentage down to 96%. The answer is 75 left-handed people must leave the room leaving 1 right-handed person and 24 left-handed people. 24 out of 25 is 96%. The easier way to calculate this is to concentrate on the number of right-handed persons which is always one. 1=4x/100 which equals 25 so there are 24 left-handed and 1 right-handed so 75 of 99 left-handed must leave the room. In the problem given the equation would be 1=2x/100 which equals 50 so there is 1 right-handed and 49 left-handed (49 out of 50 is 98%) so 50 left-handed must leave the room. This math is easier than what is shown.
Was afraid this could become a bloody affair, but al well ends well 😄! The explanation is a bit beyond the obvious, love it
50 people, 99/100 is 99% 49/50 is 98% Kevin of Vsauce2 covered this exact thing albeit with a different premise (something to do with potatoes iirc). You can also look at it the other way round, there is 1 right handed person 1 out of 100 is 1% you need it to be 2% so 1/0.02 (or 100/2) which is 1 out of 50
04:47 It would be easier to calculate this, if we would firstly multiply both sides by 100 (to get 100=2*x), and secondly divide both sides by 2 (to get 100/2 = x and x=50).
This is a great question to ask LLMs. They have lots of trouble with it...
Nah they solve it without problem
I read the thumbnail and immediately started guessing n/(n+1) values until I found the answer, then I started the video. The algebraic method and logic makes a lot of sense!
Let us assume that x people have to leave.
So, if 99/100 x 100 = 99%, then
100(99-x)/100-x = 98%
9900 - 100x = 9800 - 98x
100 = 2x
50 = x
U're wrong
Easier to look at the number who can stay. 2% means 1 in 50. So 50 stay, therefore 50 leave.
@@kotbegemot9177It'd be more helpful if u explain what's wrong instead of just saying it
@@ronald3836I wrote as how you would write in an exam or if you are bad with mental calculations
@@leaDR356 i mean that, "98%" should be "0,98" in your calculation, equation
I was given a similar question years ago in high school, and yeah, it stumped me. However, that's one of those things that only gets you once!
I solved it mentally with algebra. The hardest part was remembering the numbers, keeping them in mind. Here ‘s the equation: 99-x/ 100-x = 98/100. It took me more than 30 seconds to do it, though. Still, not bad for an octogenarian!
one of the few questions that i could actually solve! and its so satisfying to be able to solve a math question on your own without help, love it!
Easier mathematical manipulation if you recast as right-handed percentage. 1 right-handed person in the room with 99 left-handed is 99% left handed or 1% right handed. So to go down to 98%-left is to go up to 2%-right. Equation is almost the same but much quicker to solve since there is always 1 right handed peron and "x" left-handed people need to leave ther room
1/(100-x) = 0.02 Note it is easier if you recall that 0.02 = 2/100 = 1/50
1/(100-x) = 1/50 So 100-x = 50. x=50
I am sorry..I zoned out halfway through the proces and thought about if I could get the football court in recess before the other classes... just like 27 years ago when I was in math class....
to try to solve it within 30 seconds
a viable option is
98% = 98/100
reduce this fraction
49/50
luckily the original condition was 99/100 = 99%
so removing 50 from numerator and denominator (removing 50 left handed people removes 50 from total)
leads to 98%
looking at the comments, the 1% to 2% trick is even better (thinking of the complement, amount of right handed people)
1/100
2/100 = 1/50 (so removing 50 from 100)
either way, final ans 50.
I like your method, too.
I told my pal about this after it aired and he said its fairly basic maths and solved it in under 2 minutes. I had no idea but after it was explained to me it made perfect sense
99 out of 100 (initial)
98 out of 100 (final)
Final one can be written as 49 out of 50 tooo so basically u took out 50 people.
Very nice demonstration. I went the other way. The number of rightanded is constant, always 1. If 98% are lefthanded then 2% are right handed. The total number of people to have 1 person be 2% is 2/100=1/x -> 2=100/x -> 2x=100 -> x=50. W started with 100 people, so (100-50) = 50 has to leave.
my dumb ass said 2
Math just got important! Which sector of pizza is a better deal? Reddit r/sciencememes
ua-cam.com/video/Xp7ysOyTeVI/v-deo.html
Thinking through the solution in my head my own way seems so much easier than the presented equation
I solved it in 10 seconds:
If they are 100 people every person is 1%, half of those and every person equals 2% so they need to be 49 out of 50.
Same here, same reasoning, about the same time!!
Yep, but you didn’t prove it. That’s what this video is about. Finding the solution is not hard at all. Proving it is something else. Gratz though 🎉
I solved in too in a couple of seconds! I skipped the video to the end :-D
Very nice explanation.
I still haven't watched the video nor read the comments, this is how I did it:
98% = (99-x)/(100-x), which yields x = 50.
My explanation for the equation is the following. "99-x" is the final number of left-handed people in the room, x is the number of lefties who left (pun intended. Laugh!). The denominator will simply be the total number of of people in the room, which is one more than "99-x", so "100-x". Now, simply equals that with 98% and solve for x.
By the way, the addition of one more comes about because there is a right-handed, airhead strolling about this weird left-handed people congress.
Edit: yep! 👍🏻
50 lefties must leave.
-What is 1 a 2% share of?
-50
-So in a room of 100, how many people must leave to make it 50?
-50
I figured it'd be an easy enough question to do without calculator or pen and paper, so I simplified 98/100 and got the answer pretty quickly.
I love your videos! I’m terrible at math, yet I find so many elements about it (like this) so truly fascinating.
Better method to solve that algebra -
(99-x) / (100-x) = 98/100
Add and subtract 1 from 99 - x
(100-x-1) / (100-x) = 98/100
[(100-x) / (100-x)] - [1/(100-x)] = 98/100
1 - 1/(100-x) = 98/100
1 - 98/100 = 1/(100-x)
(100-98)/100 = 1/(100-x)
2/100 = 1/(100-x)
1/50 = 1/(100-x)
50 = 100-x
x = 100-50 = 50 Ans.
In order for ONE right handed person to represent 2% of the total they have to be the only one out of 50 1/50 = 0.02 = 2%. One for every 50 equals two for every hundred in percentgage terms that means the room has to lose a total of 50 left-handed people.
Only one person right handed. 2% right-handed = 1/50 so 50 left-handed have to leave the room.
Exactly.
How did u get 2% please I'm so confused. Help me
Wait I got how u got that now so is it also applicable if what I need to remove is 3%?
Like I mean if the question went Like this
In a room of 100 people, 99% are left-handed. How many left-handed people have to leave the room to bring that percentage down to 97%?
@@kingellsgaming Not without cutting people in pieces. 3/100 equals 1 out of
33 1/3. So impossible 66 2/3 persons leaves the room. I don´t like that so let us take 96% as an new example. 4% rigthhanded is one out of 25. 75 lefthanded have to leave the room. I think you got it.
I actually managed to do this as well after thinking about it for about 5 minutes and here’s my formula for this:
x/x+1 * 100 = 98%
Where x is the number of people left when there are 98% of people are left handed
and the x+1 ensures that there is still one person who isn’t left handed
With a bit of algebra you’ll get x = 49
Subtract this from 99 and your answer is 50 👏
My solution is more cogent though. We know that x people has to leave. Then the number of people remained (left-handed) is 99-x. This is 98% of the total people, so we have the equation 99-x=0.98(100-x). When you solve this, you get x = 50, which is the number of left-handed people that has to leave.
50. Basically the single right handed person is 1/100. For it to become 2/100 = 1/50, the number of left handed must decrease to 50-1=49. So from 99 to 49 is 50 left handed people must leave.
An another approach i would like to suggest goes like this:
99-x/100-x=98/100
100(99-x)= 98(100-x)
9900-100x=9800-98x
9900-9800= 100x-98x
100=2x
x=100/2
x=50
I'm surprised that I got this right when I was watching the 1% club on ITV. The way I worked it out was, 1 person makes up 2%, therefore there must be 50 people in total in the room.
Before we can solve this problem, we need to prevent the right handed person from escaping.
That's dope. I wouldn't have guessed that if I was put on the spot 😂
the easiest way to figure it out is to put the question on the reverse: how many left-handed persons need to leave the room to have the right handed guy representing 2% of the total. and now the answer is evident: 50.
I had to work my way down the list dividing until figuring out 50 people lol
Very clear explanation!
Bro, your channel is the best. :)
Because we are dealing with strictly whole numbers here, there are only a two ways a group of 100 or less can contain a subgroup comprising EXACTLY 98%. Namely, 98/100 or 49/50. The first is precluded since we start with 99/100 and we can't get to 98/100 by removing. So the second is the only outcome that fills the requirement: the number of lefties must go down by 50, leaving the original righty.
Genius, you lost me after the first 1 minute. Great work.
While you were explaining the problem I thought intuitively, 50 sounds about right.
Bros got a life time supply of markers in that cabinet. Nice
If this were a question from a TV show, the participant likely would not have had enough time to solve the equation as Steve demonstrated. Perhaps we can think of it this way:
The percentage calculation in the question is always in the form of (x-1)/x, where x is the total number of people left in the room. The required percentage, 98%, can be expressed as 98/100=49/50, which matches the form (50−1)/50.
49/50=98%, as long as that one right-handed person isn't one of the persons that leaves the room.
I love the video. I recognized the trap from manipulating probabilities and solved it from a different perspective. I watched to see if there was an alternate method and I was genuinely surprised the proof led to the same conclusion and final step.
What’s crazier is in order to get down to 97%, you’d have to remove sixteen and two thirds more left-handers from the room. To get down to 96%, you’d then have to remove eight and a third more left-handers. To decrease by 1% each time, the total people who STAY in the room must go from 100 to 50 to 33.33 to 25 to 20 to 16.66 to 14.285714 etc. Notice this follows the pattern of denominators 1/1, 1/2, 1/3, 1/4, 1/5, 1/6, 1/7 etc.
The number of people who need to LEAVE the room goes from 50 to 16.66 to 8.33 to 5 to 3.33 to 2.380952 to 1.7857142 etc. which follows a different pattern of denominators 1/(1x2), 1/(2x3), 1/(3x4), 1/(4x5), 1/(5x6), 1/(6x7) etc.
I am more impressed on how he switches his markers.
A simpler way to do this is to think of it from the right hand persons perspective, since the people we remove are only left handed, the 1 right handed person is constant, and therefore the percentage value they hold can help in calculating the rest, 1 is currently 1% of the total number of people, and since we need left handed people to become 98%, the remaining 2 % is the 1 Right handed person. So 1 went from being 1% of 100 to 2% of x. From there, it's straight forward. x*2/100=1. x=100/2=50. so the total number of people remaining in the room is 50, subtract that from the original number and you have the number of people that needs to be removed in order to match the required percentages.
This isn't hard! 99% = 1:100 (that isn't). 98% = 1:50 (that isn't). You can't control the one, so 50 have to go.
Sad that we didnt get this as a graph to easily illistrate what is happening. But nice video.
Nice seeing it all done out thoroughly.
My thought process just went "if we only have 1 righty, what number is one 2% of? Yep, 50, get rid of 50 lefties".
I know dividing by 0.02 is mathematically correct, but very few people connect the dots and realise its same as multiplying by 50... next time it would be better say: 0.02 if you multiply by 5 you get 0.1 and if you multiply by another 10 you get 1 so lets multiply both sides by 50. Its easier to understand where the number came from OR rewrite it like 2/100 and multiply by its inverse 100/2. I have math as my hobby and while i understand some calculus lvl math I struggle sometimes.. mainly with proofs but also with some complex number problems and with "curve?" integrals (not native english speaker). Thanks for your videos and effort to make more people interested in math.
also you can think of it as 1 person being equal to 1% in the beginning and at the end each person is worth 2% of the total. so you can put it in an equation where the left handed have to equal 98% and the right handed being 2% meaning that there can only be a difference of 1 person between the two groups and the only way to get to 100 this way is with 49 and 50
Originally heard this question with very watery potatoes.
(If a potato is 99% water by weight, what percentage of the weight would you need to dehydrate in order to make it 98% water)
I did it that way:
In the end, 1 (right-handed person) =2% x (x being the amount left)
50=100% x
So 50 people left, from 100 at the start, 50 left then.
I did that 1% is represented as 1/100 (per-cent, as in per every one hundred) and you want 2/100. But you only have one singular right handed person so you have to do 1/50. 100-50 is 50 people. For reference, I am 13 years old and majority of my middle school class got it right. This is a middle school question, but not all adults remember such practice.
For me, the best mental method would be to think of the right handed (1) and put it as a constante, so to have 98% of left handed it means that 2% = 1, 100% = 2*50% => 2*x=98 => x=49
Then u know the total ammount of left handed guy and the original ammount so its easy
I’m glad he wasn’t my teacher! He made that way more complicated then it had to be
I initially thought the answer was 1, but then realised that then goes from 1 right handed in a hundred to 1 in 99 which does not equate to 98%. Then I realised you need one person to be 2% of the room which means there needs to be 50 people, of which one is right handed. So to go from 100 to 50, then 50 must leave.
Funny that my brain figured out "we can't double right hand so it must be halved" almost immediately but justifying it with math took me (not the video) 5 minutes
Similar effect is seen in video games with damage and damage reduction values. 100 damage while having 90% reduction is 10 damage. Getting just 5% more to 95% reduction halves the incoming damage to 5.
Much simpler: If x is the number that (approximates or) gives a 98% ratio: x/x+1 =98/100 reduces to x=49 ie 99-50
Its pretty easy to solve in your head once you stop thinking about left handed people and start thinking of the single right handed person. Not sure if it took me more or less than 30 seconds, but somewhere in that general range.
The first thing to do is just go the brute force route and see what % will be at some nice number that you can easily multiply into 100. Like 50, which just turns out to be the answer. Or you can understand that you have 1% and need 2%, thus you need twice more, which means that you need to divide the total by two without decreasing your 1%, thus you need 50 left-handed people to leave.
Another easier calculation is to look at fixed values. Number of right-handed is 1, we need to increase from 1% to 2%
1/(100-x) = 2/100
x=50
50, 1 right handed, to double that, half the people need to leave
After finishing the video:
There are 2 simpler ways at looking at this problem.
1 & 99, what do we need to do to make 100 people = 98%, we simply replace 1 lefty with a righty, 2 & 98, and now, we can just remove half, 1R and 49L to maintain the ratio, or 50 people.
The other way is as above.
We want to make 1% become 2%, since we are doubling, we need to halve.
I think these concepts are a little more intuitive, and easier to grasp.
I wouldn't be surprised if even mathematicians spit out the wrong answer, or had to give it a bit more thought directly because they didn't look at the 1%, and instead focused on the 99%.
Easier way to calculate this: work with the fact that the number of right-handed people in the room (1) must be 2% in the final situation. If y is the total number of people in the room in the final situation, and 1 person equals 2% then y = 50.
(1/y = 2% = 2/100 = 1/50 --> y = 50)
And the number of left-handed people must be 50 - 1 = 49. So from the original 99 left-handed people, 50 have to leave.
I simply thought that I need to find a fraction where nominator and denominator differ by 1. so I thought of 49/50, which is 98/100, so 100-50=50 people have to leave the room.
1 in a 100 (1+ 99 (%)) must go to 2 in a 100 (2 + 98(%)). But we had only 1 righthanded, so 2 and 98 divided by two (in order to get 1 righthander), leaves 49 lefthanders. We had 99 lefthanders, so 50 have to go...😊