Please ignore my inclusion of the /yy early in the video, we aren't considering year - only day and month. Professional silly goose over here. More math chats: ua-cam.com/play/PLztBpqftvzxXQDmPmSOwXSU9vOHgty1RO.html Join Wrath of Math to get early&exclusive videos, lecture notes, music, and more! ua-cam.com/channels/yEKvaxi8mt9FMc62MHcliw.htmljoin
You included 'yy' in the example so the calculation would be completely different as you would have to include the odds of the year being the same which changes the problem. The video only covers the dd/mm calculation.
The bigger problems are, It should be YYYY (4 digits) and should be in the format YYYY-MM-DD, as specified in ISO 8601:2000. It has been over 2 decades, learn to write your dates correctly.
@@sdspivey Its what I do in my personal life, yes. but I live in america so gotta go MM-DD-YYYY to get by. (I'd go metric, too, if we did it). But when he says "birthday" we colloquially mean the year, too, unless otherwise state. Listen, I love this paradox. I use it in groups. But I makes sure to mention its just the month/day and not the year.
Once at a party some lady was explaining how certain dates seem to be "special," because important events happened on them. I told them about this paradox and showed that just 23 events will be enough to make it more likely to have such collisions. And it's not that hard to come up with important events. I haven't been asked on such parties since.
When you said 23 factors you weren’t totally wrong; it’s just the first factor is the probability that the first guy doesn’t share a birthday with anyone previous, which is 365/365, or 1
Most people incorrectly think about how many people it takes for 2 of them to be more likely (> 50%) to have A specific birthday, eg Dec 27. That's not the question.
I'd vaguely heard of the paradox before, but as soon as he clarified its ANY two in the room share a birthday it totally made sense to me because it's no longer just a series of 1/356, we get some addition as well. Edit: I realize I phrased that poorly... but I can't think of a better way to say it without just recapping the video, lol.. in short, his method of basically subtracting instead is simpler mathematically, but conceptualizing it as a positive is good enough to break the notion of it being a so-called paradox.
It did in mine as well because there were twins in my class haha. Eventually they left, and by senior year my graduating class was I think 27 people strong with 27 distinct birthdays.
*@ Wrath of Math* -- You could do the calculations for us for the number of people in the room where three people and four people share a birthday, and that it is likely.
It’s not the answer of people who own a same birthday/the total number of people, it’s that if 2 people in the room have a bruthday it’s gonna be a lot
This question obviously doesn't take into account that people are born more often on certain days. Example, mid October is common because they were conceived on Valentine's Day, December 25th is very uncommon because Christian mothers will deliberately avoid that day and will have the doctors induce an early pregnancy, which bloats the chances of the proceeding days.
This is true, but it's not super relevant to the problem at hand because that only makes it more likely that a small group of people would have a common birthday. So the 23 number is a worst case scenario so to speak. Assuming uniform distributions of birthdays, it takes 23 people. Accounting for the non uniformity would only increase the odds for 23 people sharing a birthday, and accounting for leap years is an insignificant change that doesn't add anything to the interest of the problem.
A twist: I belong to a Discord group of 20 people. A few months ago, we discovered that I share a birthday with two of the others. I think it's about 0.86% likely for 3 people in 20 to share a birthday. This number was greater than I expected; it's almost 1%. And for it to be more than 50%, I think it takes 75 people. I used C(group size, 3) ÷ 365² Did I do it correctly?
Please ignore my inclusion of the /yy early in the video, we aren't considering year - only day and month. Professional silly goose over here.
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You included 'yy' in the example so the calculation would be completely different as you would have to include the odds of the year being the same which changes the problem. The video only covers the dd/mm calculation.
very silly oversight! Thankfully we didn't spend too much time with the mm/dd/yy, so hopefully it won't cause confusion
Yeah, the yy is throwing this things off
The bigger problems are, It should be YYYY (4 digits) and should be in the format YYYY-MM-DD, as specified in ISO 8601:2000. It has been over 2 decades, learn to write your dates correctly.
@@sdspivey Its what I do in my personal life, yes. but I live in america so gotta go MM-DD-YYYY to get by. (I'd go metric, too, if we did it). But when he says "birthday" we colloquially mean the year, too, unless otherwise state.
Listen, I love this paradox. I use it in groups. But I makes sure to mention its just the month/day and not the year.
Once at a party some lady was explaining how certain dates seem to be "special," because important events happened on them. I told them about this paradox and showed that just 23 events will be enough to make it more likely to have such collisions. And it's not that hard to come up with important events.
I haven't been asked on such parties since.
Using maths or facts to show that superstitious stuff is nonsense appears to upset people.
I have no idea why.
@@mattsadventureswithart5764 It's bad luck, that why! :D
@@IvanToshkov @mattsadventureswithart5764 You'll both get an invitation to the next party I throw.
When you said 23 factors you weren’t totally wrong; it’s just the first factor is the probability that the first guy doesn’t share a birthday with anyone previous, which is 365/365, or 1
Yeah, I only put the correction because in the video I was specifically discussing factors less than 1. A minor slip of the tongue!
The birthday problem is a surprising and counterintuitive example, but it is NOT a ‘paradox’.
It's just called a paradox by name it isn't a paradox by the technical meaning, paradox here just means it ain't what ud think it is
Most people incorrectly think about how many people it takes for 2 of them to be more likely (> 50%) to have A specific birthday, eg Dec 27. That's not the question.
I'd vaguely heard of the paradox before, but as soon as he clarified its ANY two in the room share a birthday it totally made sense to me because it's no longer just a series of 1/356, we get some addition as well.
Edit: I realize I phrased that poorly... but I can't think of a better way to say it without just recapping the video, lol.. in short, his method of basically subtracting instead is simpler mathematically, but conceptualizing it as a positive is good enough to break the notion of it being a so-called paradox.
this actually happened multiple times in my elementary school
It did in mine as well because there were twins in my class haha. Eventually they left, and by senior year my graduating class was I think 27 people strong with 27 distinct birthdays.
Great job, best explanation I've seen to date
Thank you!
Nice Mario 64 penguin world music.
I love when mathematicians can explain their concepts with simple logic
*@ Wrath of Math* -- You could do the calculations for us for the number of people in the room where three people and four people share a birthday, and that it is likely.
Here's I am trying to learn math and you put sm64 music in the background
And sms and wind waker
It's the good stuff!
underrated
out here cooking
It’s not the answer of people who own a same birthday/the total number of people, it’s that if 2 people in the room have a bruthday it’s gonna be a lot
2:27 23
very good
Thank you!
I dont understand a single thing, i can barely remember my own birthday 😂😂
This question obviously doesn't take into account that people are born more often on certain days. Example, mid October is common because they were conceived on Valentine's Day, December 25th is very uncommon because Christian mothers will deliberately avoid that day and will have the doctors induce an early pregnancy, which bloats the chances of the proceeding days.
This is true, but it's not super relevant to the problem at hand because that only makes it more likely that a small group of people would have a common birthday. So the 23 number is a worst case scenario so to speak. Assuming uniform distributions of birthdays, it takes 23 people. Accounting for the non uniformity would only increase the odds for 23 people sharing a birthday, and accounting for leap years is an insignificant change that doesn't add anything to the interest of the problem.
Valentine’s Day conceptions are born in November, not October
@@KarlBonner1982An extremely servere case of premature ejaculation perhaps.
leap years?
leap years makes only an insignificant change.
👍
A twist:
I belong to a Discord group of 20 people.
A few months ago, we discovered that I share a birthday with two of the others.
I think it's about 0.86% likely for 3 people in 20 to share a birthday. This number was greater than I expected; it's almost 1%. And for it to be more than 50%, I think it takes 75 people.
I used C(group size, 3) ÷ 365²
Did I do it correctly?
If you use standard rounding, it reaches 99.9% at 67 rather than 75, at 99.844%, which rounds off to 99.9%
You can't say it's reached 99.9% if it's less than 99.9%, even if it rounds to 99.9%.
23hr ago 2:31
My heavens, how did you not catch the mistake before you published this video?
But i didn't see among my classmates who shares same birthday (24)
people when probabilities are probabilities
You have failed a coin toss before, right?