This was a ratio question 6' cast 15' which is shaddow is 2.5 times the length of persons height , therefore tree shadow length is 2.5 times the length of the height of the tree Therefore 100/2.5 = 40 super simple
Ok, that’s a relatively easy ratio to work out, but what if it had been 7:15 for example . You need to explain mathematically first and foremost, that part of the problem
And you cut out all the nattering that was rather annoying , if he said tall man once more I was stopping watching 😂 , it was a long way for a shortcut
Consider that not everyone knows all that you know! They come here to LEARN STEP BY STEP! Why do you want to make them feel inferior? Remember, there was a time YOU were like them!
@@lamper2 fair enough , I'm not good at maths but found this laborious in parts , just too much talk and ads which has nothing to do with the equation , if the person wants to chat about their life etc they could do it at the beginning or end and I never said anything about learners of maths , as another comment said a bit long winded
I'm sorry, you sound like a nice guy, but at the already WAY over time 16:26 mark you said, 'Well, you know, I don't wanna make this video over lengthy' and then spent a further 2 mins getting to the actual answer. 🤔 This problem was EXTREMELY simple and you could have explained the whole thing concisely to ANY audience in under 2 mins. You went on SO long that I literally watched the video sheerly out of interest to see how long you could actually stretch out such an easy problem. 🥱 A point of note is, that you said SO much that you remind me of times that school teachers would baffle fellow students with overload/overcomplication. I'd get it, but could see clearly how the teacher was confusing others. If you want people to be interested in math and engage in your channel, I'd recommend NOT making 20 min videos to explain 2 min problems. Triangles? Proportions? Algebra? Ratio? Diagrams? 😵💫🤯 My 10 year old performed this calculation in 2 mins by just making the 15 and the 100 the denominators of fractions and then the lowest CD is obviously 300. Multiply the numerator of the 'man's' fraction by 20 (300÷15) and the numerator of the 'tree's' fraction by 3 (300÷100). The man's fraction is 6/15 or 120/300. So, the tree's fraction must also be the same (proportional). Therefore, factoring back down by 3 from the 120/300 gives the tree height as the numerator = 40/100 In other words, all he had to use was simple multiplication and basic knowledge of fractions to solve this. Although your presentation was good, your video was far TOO long. Anyone not good at maths would have lost interest quite quickly and possibly been even more confused than when they started. P.S. Good point about common sense though. A and B are clearly wrong. lol!
6 is to 15 as x is to 100 6 is to 15 = 2 is to 5 100÷5=20 20×2=40 UTILIZING dimensions --> man to shadow= (6/15) height/shadow resolved (6/15) = 2/5 height-ft/shadow-ft = 4/10 height-ft/shadow-ft = 0.4 height-ft/shadow-ft this is the sun's position 0.4 height-ft/shadow-ft given tree shadow = 100 shadow-ft solution 100 shadow-ft × 0.4height-ft/shadow-ft = 40 height-ft. notice how "shadow-ft" in numerator and denominator cancel!
It's simple, use either methods as follow :- (Man's shadow) 15 : [To] (his hight) 6 (Tree's shadow) 100 : [To] (its hight) ? Using the cross method, therefore;- 15×? = 6×100 ?=6×100÷15 ?=600÷15 ?=40 (Tree's hight) OR you can use this method;- Get the ratio between the man and his shadow, then use it to findout the tree's hight like so;- 15 (shadow) : 6 (hight) = 15÷6=2.5 Means that the man's shadow increased 2.5 times to his hight. Therefore, to findout the tree's hight divide its shadow by 2.5 100÷2.5=40 (Tree's hight) Notice that 100 (T. shadow) ÷ 40 (T. hight) = 2.5 times as well, same proportionality as the man's shadow. I just have a little correction to the video's tittle, it has to be: the tree if (its) shadow 100ft NOT if (it's) shadow 100ft 😀
This one is quite easy again: the shadow is in a ratio of 6 ft vertical to 15 ft horizontal so 6/15 = 2/5 feet vertical for every feet horizontal. The shadow of the tree is 100 ft so the height of the tree is 100 x 2/5 = 200 / 5 = 40 ft No calculator needed of course! So answer D.
I know the ratio - cross multiply technique, but as this multiple choice I note that 15×7= 105, a little higher than 100 And 6×7=42, a little higher than 40 So choose D without writing anything down. Grease through these multiple choice problems.
Greetings. The answer is 40ft tall. Using the properties of similar triangles, and assuming that the tree is X ft tall, we have 15/100=6/X. Solving for X gives 15X=600 ft, and X=600/15 ft.
I solved it by dividing 15 by 6 = 2.5 then dividing 100 by 2.5 =40. You can also divide 6 by 15= 0.4 and multiply 100 by 0.4 =40.Both ways involve a ratio that you either divide by or multiply by. Are these methods sound mathematically or can they lead to errors?
At the title card (0.07), no calculator or paper, my answer is d) 40'. Since the 6' man casts a 15' shadow, his shadow is 5/2 times his height. 100' divided by 5/2 would be (100/1)/(5/2), or (100/1)*))2/5). (100/1)*(2/5) = 200/5) = 40.
I need help in this problem Q.After buying any item a person sells it at 10% loss. if now he buys it 20% Less cost and sells it at Rs 55 more then his profit is 40%. then find its cost price?
OMG my brain just exploded because it took you 22 minutes to say since 6 is slightly less than half of 15 then the answer must be 40 since it's a multiple choice problem and 40 is slightly less than half of 100.
6 ft tall man X tree height _____________ = _______________ -->cross multiply 6ft x 100ft = 15ftx --> solve for x --> 600/15 = 40 ft tall the tree is. 15 ft shadow 100 ft shadow
Man's shadow, 15 ft is 2.5 times as long as the man is tall, 6 ft. so the tree's shadow will be 2.5 times as long as the tree is tall, ASSUMING that both shadows were measured at the same time! 100 divided by 2.5 is 40. (100 divided by 25 (2.5 x 10) = 4, is even easier, and then multiply that by 10 for 40.)
I said d) 40' because 40 is the highest number choice given and most trees are at least or more than 40' tall. Instead of math, I used botany to solve this one. :)
Please excuse the past text that came out wrong. I took the height of a man and a shallow six15s equals 2/5 2/5 of 100 is 40 and that’s the answer. Thank you I know it’s different but that’s why I got it.
Ambiguous question yet again. Depends where the light is coming from, what the shadow is projected on to, whether the man is standing up or not, and more.
Where is the light source ? How can you say that the solution is 40 if you dont know where is the light ? I suppose that you think the light is the sun. Then the solution is easy. But if the light is a street light ?
40ft. While we’re in the educational sphere, why not get the English correct as well - it should be « its shadow » without an apostrophe. «It’s » can only mean « it is » or « it has ».
20mins of over complicating. For a 10second question of %. 100/15 × 6= 40% 15=100% Tree height =40% of tree shadow Tree height =40ft... and even i over explained it.
Answer is 40ft not 40 inches. 40 inches is 3feet 4 inches . So do you mean to tell me that an object casting a 100 ft shadow is shorter than the man casting a 15 ft shadow.
More interesting approach to this problem would be to invite responses in terms of how many ways can the correct anwer be found. I got it right but with a different approach
This was a ratio question 6' cast 15' which is shaddow is 2.5 times the length of persons height , therefore tree shadow length is 2.5 times the length of the height of the tree Therefore 100/2.5 = 40 super simple
Ok, that’s a relatively easy ratio to work out, but what if it had been 7:15 for example . You need to explain mathematically first and foremost, that part of the problem
@@beaumoa100What do you mean? Their answer is complete. What more were you expecting?
its, not it's. Its is possessive.
Every 2' casts a 5' shadow. 100/5 = 20; 20x2 is 40'. I did it in my head in about a minute.
And you cut out all the nattering that was rather annoying , if he said tall man once more I was stopping watching 😂 , it was a long way for a shortcut
Consider that not everyone knows all that you know! They come here to LEARN STEP BY STEP! Why do you want to make them feel inferior? Remember, there was a time YOU were like them!
move on to Calculus and let others make fun of YOU!@@smallfeet4581
@@lamper2 fair enough , I'm not good at maths but found this laborious in parts , just too much talk and ads which has nothing to do with the equation , if the person wants to chat about their life etc they could do it at the beginning or end and I never said anything about learners of maths , as another comment said a bit long winded
40'
got it 40 simple ratio 6/x = 15/100 is one way. thanks for the fun. 6/15 = x/100 is another way.
100 ÷15 x 6 = 40
I think d) 40' . 1mn mental calculation.
15÷6 = 2.5
100 ÷ 2.5 = 40
Exactly. Keep it basic and simple.
I'm sorry, you sound like a nice guy, but at the already WAY over time 16:26 mark you said, 'Well, you know, I don't wanna make this video over lengthy' and then spent a further 2 mins getting to the actual answer. 🤔
This problem was EXTREMELY simple and you could have explained the whole thing concisely to ANY audience in under 2 mins. You went on SO long that I literally watched the video sheerly out of interest to see how long you could actually stretch out such an easy problem. 🥱
A point of note is, that you said SO much that you remind me of times that school teachers would baffle fellow students with overload/overcomplication. I'd get it, but could see clearly how the teacher was confusing others.
If you want people to be interested in math and engage in your channel, I'd recommend NOT making 20 min videos to explain 2 min problems.
Triangles? Proportions? Algebra? Ratio? Diagrams? 😵💫🤯
My 10 year old performed this calculation in 2 mins by just making the 15 and the 100 the denominators of fractions and then the lowest CD is obviously 300.
Multiply the numerator of the 'man's' fraction by 20 (300÷15) and the numerator of the 'tree's' fraction by 3 (300÷100).
The man's fraction is 6/15 or 120/300.
So, the tree's fraction must also be the same (proportional).
Therefore, factoring back down by 3 from the 120/300 gives the tree height as the numerator = 40/100
In other words, all he had to use was simple multiplication and basic knowledge of fractions to solve this.
Although your presentation was good, your video was far TOO long. Anyone not good at maths would have lost interest quite quickly and possibly been even more confused than when they started.
P.S. Good point about common sense though. A and B are clearly wrong. lol!
@@nrich99999 LONG monotonous tone , this was the reason I fell asleep in class 😂 ,,
@@nrich99999unnecessarily overlong and repetitive, says the man who just wrote a 20 paragraph diatribe to tell us this!
@@adamsmith4813 To be fair Adam, I thought that myself as I was writing it. lol! Fair point! 👍
6 is to 15
as x is to 100
6 is to 15 = 2 is to 5
100÷5=20
20×2=40
UTILIZING dimensions -->
man to shadow=
(6/15) height/shadow
resolved
(6/15)
= 2/5 height-ft/shadow-ft
= 4/10 height-ft/shadow-ft
= 0.4 height-ft/shadow-ft
this is the sun's position
0.4 height-ft/shadow-ft
given tree shadow
= 100 shadow-ft
solution
100 shadow-ft
× 0.4height-ft/shadow-ft
= 40 height-ft.
notice how "shadow-ft" in numerator and denominator cancel!
It's simple, use either methods as follow :-
(Man's shadow) 15 : [To] (his hight) 6
(Tree's shadow) 100 : [To] (its hight) ?
Using the cross method, therefore;-
15×? = 6×100
?=6×100÷15
?=600÷15
?=40 (Tree's hight)
OR you can use this method;-
Get the ratio between the man and his shadow, then use it to findout the tree's hight like so;-
15 (shadow) : 6 (hight) = 15÷6=2.5
Means that the man's shadow increased 2.5 times to his hight.
Therefore, to findout the tree's hight divide its shadow by 2.5
100÷2.5=40 (Tree's hight)
Notice that 100 (T. shadow) ÷ 40 (T. hight) = 2.5 times as well, same proportionality as the man's shadow.
I just have a little correction to the video's tittle, it has to be: the tree if (its) shadow 100ft NOT if (it's) shadow 100ft
😀
This one is quite easy again:
the shadow is in a ratio of 6 ft vertical to 15 ft horizontal so 6/15 = 2/5 feet vertical for every feet horizontal.
The shadow of the tree is 100 ft so the height of the tree is 100 x 2/5 = 200 / 5 = 40 ft
No calculator needed of course!
So answer D.
I know the ratio - cross multiply technique, but as this multiple choice I note that 15×7= 105, a little higher than 100
And 6×7=42, a little higher than 40
So choose D without writing anything down. Grease through these multiple choice problems.
2.5X = 100 using equal ratios
Then from choices
d) 40 fits equation from head.
6 divided by 15 =.4 then x 100 =40
Keep it simple to reduce the time, unless you’re studying to be a math teacher.
When I was studying to become a teacher math and physics I was taught to keep it simple.
Or 15÷6=2.5. 100÷2.5=40.
Greetings. The answer is 40ft tall. Using the properties of similar triangles, and assuming that the tree is X ft tall, we have
15/100=6/X. Solving for X gives
15X=600 ft, and X=600/15 ft.
I solved it by dividing 15 by 6 = 2.5 then dividing 100 by 2.5 =40. You can also divide 6 by 15= 0.4 and multiply 100 by 0.4 =40.Both ways involve a ratio that you either divide by or multiply by. Are these methods sound mathematically or can they lead to errors?
Thank you
150% was the magic number I came up with to answer of 40'
Smae here or 2.5
Multiple ways. One way besides using tan, is knowing the angle is the same, how many times is 15 into 100, finding the ratio to multiply 6.
How ignorant is a person who doesn't know "it's" from "its"?
At the title card (0.07), no calculator or paper, my answer is d) 40'.
Since the 6' man casts a 15' shadow, his shadow is 5/2 times his height.
100' divided by 5/2 would be (100/1)/(5/2), or (100/1)*))2/5).
(100/1)*(2/5) = 200/5) = 40.
You are as long-winded as Euclid is old, but these puzzles are fun and they show the real-world application of mathematical theory.
Surely you don't take all that round the houses approach in the real world. Just divide it by 2.5 as is 6/15
6/15=0.4 is the ratios height to shadow.
100 ft shadow to height of tree is 100 x 0.4=40 ft
D) 40.
I have one question:- The half of the cubic root of √64 ?
I did it slightly different.
15/6=2.5.
100/2.5=40. This is an "introduction to algebra" problem.
I need help in this problem Q.After buying any item a person sells it at 10% loss. if now he buys it 20% Less cost and sells it at Rs 55 more then his profit is 40%. then find its cost price?
My kids will definitely find value in this!
OMG my brain just exploded because it took you 22 minutes to say since 6 is slightly less than half of 15 then the answer must be 40 since it's a multiple choice problem and 40 is slightly less than half of 100.
I got chastised for mentioning the time it took , I think they get more money the longer they are on lol,
6’ x 2.5 is 15’
40’ x 2.5 is 100’
Prolem solved
I did it different. I put 6/15 which is 2/5 to fish of 140 feet. That’s why I did it.
D. Because 6/15 which is 2/5 which is 4/10 or 0.4 times 100 is 40
6 ft tall man X tree height
_____________ = _______________ -->cross multiply 6ft x 100ft = 15ftx --> solve for x --> 600/15 = 40 ft tall the tree is.
15 ft shadow 100 ft shadow
Man's shadow, 15 ft is 2.5 times as long as the man is tall, 6 ft. so the tree's shadow will be 2.5 times as long as the tree is tall, ASSUMING that both shadows were measured at the same time! 100 divided by 2.5 is 40. (100 divided by 25 (2.5 x 10) = 4, is even easier, and then multiply that by 10 for 40.)
40. 6 times 100 divided by 15 equals 40
I said d) 40' because 40 is the highest number choice given and most trees are at least or more than 40' tall. Instead of math, I used botany to solve this one. :)
How many 15' shadows from a 6' man, make a 100' shadow?
100÷15×6=40
I'm not sure how I did mine.
6 is to 15 as X is to 100
6/15 = X/100
15X = 600
X = 40
48ft d40'
Shadow is 2.5 times height of man, so tree is 2.5 times smaller than its shadow.
6ft x 2.5 = 15ft shadow
100ft ÷ 2.5 = 40ft tree.
😎
100/15 *6=600/15=40’
Now that I read the question three times, I see that the shadows are cast simultaneously.
40
Please excuse the past text that came out wrong. I took the height of a man and a shallow six15s equals 2/5 2/5 of 100 is 40 and that’s the answer. Thank you I know it’s different but that’s why I got it.
That was too easy. You guys are turning me into a conceited monster.
A grade 7 monster
Ambiguous question yet again. Depends where the light is coming from, what the shadow is projected on to, whether the man is standing up or not, and more.
40 x2.5 = 100. 6x 2.5 = 15
Where is the light source ? How can you say that the solution is 40 if you dont know where is the light ? I suppose that you think the light is the sun. Then the solution is easy. But if the light is a street light ?
Jesus, how long winded was that? 100ft/15ft then times the height of the man ,job done
Yes, there’s simpler ways to solve this, but he’s teaching geometry. Let’s not lose sight of that.
Now that I have read the question three times, I believe "it's" is a contraction for it is. "Its" is the possessive pronoun.
I just multiplied both sides by 100 to make x by itself, and then divided by 15, which gave me 40.
40 is what I had divded 100 by 15 then multipled 6.666x6=40
I divided 6 by 15 and 0.4 and multiplied that times 100 and got 40
40ft. While we’re in the educational sphere, why not get the English correct as well - it should be « its shadow » without an apostrophe. «It’s » can only mean « it is » or « it has ».
And what is a “prom” and the meaning of the noun a “wrong”? Where to buy one of those?
The answer is A 6.7
40 ft.
20mins of over complicating. For a 10second question of %.
100/15 × 6= 40%
15=100%
Tree height =40% of tree shadow
Tree height =40ft... and even i over explained it.
d). 40’.
Wow you really made this complicated.
I also did it mentally and came up with 40
40 ft
40’?
d)40’
The answer depends on whether the sun is rising or setting.
D 40 feet
If he is standing at the tree to block the sun then he is not casting a shadow
Answer is 40ft not 40 inches. 40 inches is 3feet 4 inches . So do you mean to tell me that an object casting a 100 ft shadow is shorter than the man casting a 15 ft shadow.
Where does he mention inches?
D..40'
40'
40 feet
Ratio: 40.
6.7
35???
6x100 and divide by 15x =40 heard answer but figured it out
d) 40 ft.
Ratio and proportion. Height/shadow equals height of tree/shadow
ft is not even a thing.
You are great but way too wordy. Lost interest but hung in there.
More interesting approach to this problem would be to invite responses in terms of how many ways can the correct anwer be found. I got it right but with a different approach
@@beaumoa100I just divided it by 2.5 as is 6/15
Yes, he does talk too much but believe it or not sometimes he still doesn't explain enough, on very rare occasions (< 2%)
This guy's English is terrible.
B
D
You talk too much.Get to the point! .
40
40 ft.
40 feet
40 ft
40
40
40
40
35
40 feet