Check your intuition: The birthday problem - David Knuffke

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  • Опубликовано: 30 сен 2024
  • View full lesson: ed.ted.com/less...
    Imagine a group of people. How big do you think the group would have to be before there’s more than a 50% chance that two people in the group have the same birthday? The answer is … probably lower than you think. David Knuffke explains how the birthday problem exposes our often-poor intuition when it comes to probability.
    Lesson by David Knuffke, animation by TED-Ed.

Комментарии • 2,4 тыс.

  • @simexn
    @simexn 7 лет назад +9242

    i dont even wanna know how difficult the editing of this video was

    • @minecraftminertime
      @minecraftminertime 7 лет назад +158

      Don't worry, I'm sure the lines to each weren't added in manually

    • @JoseLuisHaro
      @JoseLuisHaro 7 лет назад +88

      i was thinking the same in stead of the math

    • @NilanjanPaul
      @NilanjanPaul 6 лет назад +38

      Shut up! You're Hermione. 😁 You must be good in Maths 👍

    • @aaryasharma9781
      @aaryasharma9781 5 лет назад +14

      Hello Hermione

    • @priyankasudula764
      @priyankasudula764 4 года назад +3

      pxrenatxre
      Hi

  • @madina6689
    @madina6689 4 года назад +4710

    When you figured you just watched a full math lesson willingly

    • @youtuber-nx5en
      @youtuber-nx5en 3 года назад +35

      I am just reading comments over here.... Not watching the video... 😂😂😂😂

    • @lunaromance2243
      @lunaromance2243 3 года назад +9

      I wanted to test my intuition but I realized I had solved this exact problem a few days ago😭😆

    • @AnthonyGameFilms
      @AnthonyGameFilms 3 года назад +1

      Lmao true

    • @evableichenbaum5673
      @evableichenbaum5673 3 года назад +3

      I wish Math in school was this interesting 😅

    • @elizabethcorum3772
      @elizabethcorum3772 3 года назад +2

      Nah I just dipped at 1:45 😂

  • @virginialira9477
    @virginialira9477 4 года назад +3967

    "ignore leap years"
    me a person born in February 29th: ok then

  • @notjustastopmotion6493
    @notjustastopmotion6493 4 года назад +7162

    I had three people in my class who all had the same birthday. Same month, same year, same day. Funny thing was, they’re all best friends

    • @aditisk99
      @aditisk99 4 года назад +387

      Wow ,they wouldn't call anyone to their party then.

    • @saloni.sharma
      @saloni.sharma 4 года назад +153

      Me and my best friend have same birthday too. Not same year tho.

    • @epiclady2000
      @epiclady2000 4 года назад +123

      And that’s on zodiac signs

    • @xraaaxcaaar2779
      @xraaaxcaaar2779 4 года назад +166

      My best friend and I had the same birthday, we even have the same first name. She is one hour older than me.

    • @SKyrim190
      @SKyrim190 4 года назад +71

      Same year in a school class is not so uncommon because you are already divided by age

  • @sanjivanie8221
    @sanjivanie8221 4 года назад +5655

    "take a moment to think about it"
    Me: bold of you to assume I think

  • @pauljk-123
    @pauljk-123 7 лет назад +5844

    Funny thing is in my 10 years of school with an average of 25 students in the class, nobody had shared birthdays

    • @AlecXiaxxy
      @AlecXiaxxy 7 лет назад +263

      Lelouch Yagami did you ask for everyone's birthday? did you consider the birthday's over the weekend, holidays, and breaks?

    • @sherlockholmes2317
      @sherlockholmes2317 7 лет назад +181

      Lelouch Yagami Because the year that you and your classmates are born on are the same so the chances decrease

    • @pepesilvia6682
      @pepesilvia6682 7 лет назад +793

      No, the fact that they were born on the same year has no effect on the probability two people had the same birthday.

    • @aidacempaka8828
      @aidacempaka8828 7 лет назад +70

      Well in my class of 38 none share a birthday but I have a fren that's birthday is one day before me

    • @dianewin7094
      @dianewin7094 7 лет назад +65

      Yeah same! I have only met one person in my life that shares the same birthday as me! Even as I did extra-school classes

  • @tallvictorieshr1783
    @tallvictorieshr1783 4 года назад +1902

    i didn’t understand like any of that but yum cupcakes

    • @lalina7380
      @lalina7380 4 года назад +13

      Lmao

    • @MRTRASH-cj3dl
      @MRTRASH-cj3dl 4 года назад +5

      😂😂

    • @danelreahnparas4897
      @danelreahnparas4897 3 года назад +7

      It's all about having the same bday in a group.

    • @viiidii7940
      @viiidii7940 3 года назад +1

      Lnaoo same

    • @rozhin6055
      @rozhin6055 3 года назад +7

      Literally me. Not only did I not understand the video, but now I'm craving cupcakes 😭😭🤦🏻‍♀️

  • @elliotalderson4873
    @elliotalderson4873 7 лет назад +1107

    My intuition: Ok let's try to find out what the answer could... urgh it involves math calculation sorry i can't do nothing for you

    • @athrasher4160
      @athrasher4160 7 лет назад +38

      You can't do nothing? That's a double negation, which means that you can solve it. I'll be waiting for your solution.

    • @declanmcgill4490
      @declanmcgill4490 7 лет назад +6

      aThrasheR shhhhhhut up

    • @tcxd1164
      @tcxd1164 7 лет назад +18

      aThrasheR
      Even though that's a double negation, it's sort of a slang (maybe) some people use to make a single negation.
      There might be an explanation somewhere, but I'm too lazy to search for it.

    • @misse1228
      @misse1228 7 лет назад +15

      It's not slang, it's just grammar. Most languages outside of the Germanic language family actually REQUIRE the use of double negation (French, Spanish, Portuguese, etc.). There are also dialects of English that use double negatives (AAVE being one of them).
      It's a huge myth that double negatives make a positive, when talking about language.

    • @athrasher4160
      @athrasher4160 7 лет назад +6

      I speak French and I can tell you that the "double negation" you're talking about that is required isn't actually one. It's just one negation that requires two words and that's totally different. An actual double negative in French makes a positive.

  • @donnameyer7181
    @donnameyer7181 3 года назад +579

    My initial guess was about 24. As a classroom teacher, I notice it is common for a shared birthday to occur about every other year or so. Having just looked at my roster today, and specifically the birthdays, I did notice a shared birthday this year. So I based my guess on experience rather than statistics!

    • @asha_4095
      @asha_4095 3 года назад +20

      Ahh I see. I guess teachers have seen the amount of shared birthdays per class/grade. As a student I guessed around 100 people. My graduating class has around 300 kids and i share a birthday with 3 of them. Crazy rightt

    • @supersamdadsacount9918
      @supersamdadsacount9918 Год назад

      My guess was infinity

    • @bluescrud8879
      @bluescrud8879 Год назад

      wow thats so cool

    • @andrewcuber8968
      @andrewcuber8968 Год назад

      interesting!

  • @ludominguez4176
    @ludominguez4176 4 года назад +569

    The probability of a match
    A MATCH
    So many good jokes

  • @simplymaci
    @simplymaci 7 лет назад +919

    What a coincidence! You uploaded this on my birthday 😂🎂✨

    • @h.z6870
      @h.z6870 6 лет назад +24

      simplymaci may the 4th be with you

    • @oceanaesther
      @oceanaesther 6 лет назад +6

      It was my birthday too!

    • @izzytheemo1174
      @izzytheemo1174 6 лет назад +1

      It's my sister's birthday on May 4th too.

    • @Banzybanz
      @Banzybanz 6 лет назад +11

      With such massive number of viewers its not a big deal. There are thousands like you.

    • @artymclabin8584
      @artymclabin8584 6 лет назад +3

      simplymaci , as well as in the birthday of another 2000~ viewers of this video

  • @cup_check_official
    @cup_check_official 7 лет назад +1039

    To anyone reading this comment, its not my birthday.

  • @TEDEd
    @TEDEd  7 лет назад +1099

    Sorry for the double upload! We had to fix a quick error and wanted to get you all the corrected video right away. Here it is -- please enjoy and thanks for watching!

    • @chubbygamer464
      @chubbygamer464 7 лет назад +6

      TED-Ed yay!

    • @Serhio0o7
      @Serhio0o7 7 лет назад +10

      Now i want to know what the error was.

    • @GamerFlicks
      @GamerFlicks 7 лет назад +6

      TED-Ed can i get a answer to my answer? Sometimes we hit special point on elbow on anything and it pains tooo badly and feels like being shocked. Please could you explain it

    • @atsumindesu
      @atsumindesu 7 лет назад +9

      Inder Saini it's because in that spot there is a nerve that is really exposed, and unlike other nerves protected by bones or other things this one is really easy to touch and hit accidentaly. The pain is horrible because muscles are very weak to that stuff.

    • @GamerFlicks
      @GamerFlicks 7 лет назад +2

      ΠІΠЈΛ uh thnks bro 😳

  • @annieyu72
    @annieyu72 6 лет назад +548

    I wonder how after all of my years at school, I’ve never met a person with the same birthday!

    • @bmr208
      @bmr208 5 лет назад +3

      Same

    • @soumya2972
      @soumya2972 4 года назад +4

      Nopes.. Infact i had shared my birthday once with my classmate 😅😅 who was just my partner 😵...
      What a boomer it was for me!

    • @joannaxuan4265
      @joannaxuan4265 4 года назад +12

      @@abbreviatedalex2418 This is so true. I used to think that it would be impossible to find someone who shares my birthday, or at least that I haven't met anyone who shares my birthday, but then I ran into a friend in London (We're both chinese) and then to our surprise we realised that we had the same birthday.
      (and then I forgot about it because the idea that someone shared my birthday was still foreign to me, so I forgot to wish her happy birthday on my birthday 😢)

    • @anavybluemystery3486
      @anavybluemystery3486 4 года назад +33

      because it's any two people not you and someone else

    • @kriti4698
      @kriti4698 4 года назад +4

      I share my birthday with my own brother who's 8years elder than me.

  • @leahmaloney7540
    @leahmaloney7540 4 года назад +202

    this made statistics sound a lot more interesting suddenly I remember doing combinations

  • @muhammadfadlullah5585
    @muhammadfadlullah5585 7 лет назад +904

    I just think the other factor why our basic intuition can't grasp the math is because our brain have small room to imagine the pairs. I mean, when this question come up, people tend to imagine about to pair their own birthday with just small group people, abandoning that each of one in 23 is pairing with others. So, this makes first dial signal into our brain that "it is hard to find match YOUR birthday with only 22 people". Then we end up realize that "Oh yeah this question supposed to pairs each people, not only one"

    • @alexxmde
      @alexxmde 6 лет назад +4

      Muhammad Fadlullah hey, nice thought!

    • @AladynG
      @AladynG 4 года назад +13

      which means that humans are kinda selfish, they only think of their own perspective of things and ignore others

    • @insertnames
      @insertnames 4 года назад +29

      @@AladynG yes but, evolutionary, this makes perfect sense. we wouldn't have been able to survive if we "wasted time and resources" thinking about others instead of putting ourselves into the centre of our thoughts

    • @bond-potter-morriarti7194
      @bond-potter-morriarti7194 4 года назад +4

      @@insertnames well played

    • @Lene-ib7qz
      @Lene-ib7qz 3 года назад +1

      True!!

  • @Johnny_BGood
    @Johnny_BGood 7 лет назад +442

    I just have to say, that the editing of the video is amazing and pretty entertaining, I love it!

  • @mich3134
    @mich3134 4 года назад +158

    I have a friend who was born on the same yr, same day, in the same city, in the same hospital as me! We were born just hrs apart from each other. We just so happened to meet at a summer camp on Atlanta when we were 22!

    • @TheSonshineKids
      @TheSonshineKids 3 года назад +1

      Me too. At 29, but in the workplace.

    • @RspbyLmn
      @RspbyLmn 3 года назад +2

      Sounds like the beginning of the Disney Ckassic "The Parent Trap". Lol

  • @DaveTexas
    @DaveTexas Год назад +42

    In my first psychology class in college, the professor used this as a way to show that people’s intuition and "common sense" is often wrong. While it’s really a mathematical puzzle, the fact that most people are wrong about this gives us insight into psychology.
    The class had about 150 students in it. The professor had each of us guess how many people he’d have to call on to find two who had the same birthday. We all wrote down our answers, then he had us sit in sections of the lecture hall based on the number we’d chosen. Most people selected a number greater than 150, reasoning that you’d have to go through birthdates for half the year before you were likely to find a match.
    He then started asking each student what their birthdate was. He’d write the date on the chalkboard. We reached the first match at like the 12th person he called on. He said that we’d throw that result out since it was just coincidental that we’d found a match so quickly. He kept going. The next match happened on about person number 21. He kept going, wanting to show us where we’d reach a point where almost every new birthdate was a match. We got there by person number 60-something. By the time we were into the 70s, pretty much every new birthdate matched someone else’s.
    He explained the mathematics behind it, yet there were still people in the class that said it was impossible to have so many matches in a group that small. He asked them to explain why it worked, though, since we’d all seen it with our own eyes. They said it just defied common sense. The professor said that this is why "book smarts" almost always trumps "common sense." Most people simply can’t comprehend that.

    • @Frozpls
      @Frozpls Год назад +1

      Ego is quite a strange tool

  • @navi9764
    @navi9764 3 года назад +50

    I have watched so many ted ed videos that Addison Anderson's voice comes to me in my dreams.

  • @477-c4z
    @477-c4z 7 лет назад +217

    *BEEP*
    *BEEP*
    [Incoming "today is my birthday" comments alert]

  • @ryanl9902
    @ryanl9902 7 лет назад +200

    I don't understand any of this but I still love it

    • @dariocardajoli6831
      @dariocardajoli6831 5 лет назад +1

      Wtf??? How???

    • @friahakim1523
      @friahakim1523 4 года назад +1

      Me toooooo

    • @bengal_tiger1984
      @bengal_tiger1984 4 года назад +2

      Want an explanation?

    • @sadpowie
      @sadpowie 4 года назад +4

      @@bengal_tiger1984 sure I have difficulty understanding too

    • @bengal_tiger1984
      @bengal_tiger1984 4 года назад +11

      There are 365 days in a typical year. Our scenario works without accounting for leap years, twins etcetera.
      So we have 23 people in a room right? Our current aim is to calculate the probability of 23 people NOT sharing a birthday.
      Let's start off with the chances that two people have the same birthday. The first person who we will call Allie can have a birthday any day of the year. So now we account for that particular birthday, we assume that the next person Blair can only have their birthday in all of the remaining days of the year (her birthday is not the same as Allie's.)
      You know how when you roll a single die, you ask yourself what is the chance that you will have a five followed by a four? Without considering the many variables in our world and only concentrating on pure probability, we multiply the 1/6 by 1/6. It doesn't really matter whether what the following number is four or whatever; it is independent of repetition since it is a single die. The probability of getting this combination is 1/36 now. Same with unbiased coins, probability of getting two heads in a row is the same as a head followed by a tail.
      This connects to the birthday problem as the probabilities are all multiplied. For Allie and Blair, we would say 365/365 * 364/365 which gives us roughly 0.9972 so the percentage is 99.72%. That is the probability that Blair and Allie DO NOT share the same birthday.
      Now let us return to the scenario with 23 people in the room. We do the same as we did for Blair and Allie, but just as we reduced the numerator by 1 for Blair, we keep repeating. 365/365 * 364/365 * 363/365... Until we reach 365 - 23 (for the people in the room) which is roughly 342. Then we multiply all of these. After that, we divide that answer by 365 to the power of 23 as you can see that 365 has been multiplied by itself 23 times. We didn't have to do this to Allie and Blair previously as Allie's 365/365 cancelled out and made 1. But that is how we attain the probability of none of the 23 people sharing the same birthday. That is roughly 0.4927 or 49.27%. Now by deducting by 1 or 100, we get 0.5073 or 50.73%. That is the probability that at least two people in this group of 23 share the same birthday!
      To make this easier, we can use the formula n!/(n - k)! /n ^ k. n represents the number of days in the year here, which is 365. k is the number of people in the group here, which is 23. As explained, 365 is multiplied 23 times so it is divided by 365 to the power of 23. The factorials make it easier rather than the tedious reduction process (it'd be a pain to repeat those fractions 23 times!) as they are after all multiplied by each other in order such as 1 * 2 * 3 could just be written as 3!. Yes, you noticed how different the formula looks from the method we used with the factorial of n on the numerator and the n - k in the denominator but it reflects that process of ours basically.
      Hope this explanation helped you understand... Feel free to ask any more questions and point out any errors! Now try one of your own, what is the probability that out of a group of 10 friends, at least two share the same classes in a school with 50 different class options? (Made this one on the fly...)

  • @kushagraverma6456
    @kushagraverma6456 3 года назад +57

    *"why was our Intuition so wrong"*
    No honey, it aint , Im bad at math!

  • @poooopoo
    @poooopoo 4 года назад +98

    0:50 "why is our intuition so wrong" me who guessed 25 when the answer is 23... 👁👄👁

    • @sr.charmander._.7095
      @sr.charmander._.7095 4 года назад +2

      Same

    • @ragnarok4294
      @ragnarok4294 3 года назад +1

      I guessed 26😁

    • @elmondo-s1e
      @elmondo-s1e 3 года назад +2

      I don’t get the point of this comment/replies. You got it wrong so you’re saying “lol intuition is so wrong cause I was wrong” but also you’re telling us your guess which is close but out by a few so are we supposed to be impressed by this!? I’m so confused hahaha what is your INTENT, PEOPLE

    • @poooopoo
      @poooopoo 3 года назад +5

      @@elmondo-s1e i was mocking the quote from the video by pointing out my own answer which was close, basically sarcasm cause intuition can actually be correct

    • @JeansWebbTv
      @JeansWebbTv Месяц назад

      Good guess, but also: we are helped by the fact that we are watching a youtube clip and therefore understand that the answer must be suprisingly (?) low.
      If the same question would have been asked in a more boring context, I guess our guesses would be different.

  • @mariusalexandrubirla1751
    @mariusalexandrubirla1751 7 лет назад +646

    It's my birthday! I'm 24 now! Happy birthday to me!

  • @GuildOfCalamity
    @GuildOfCalamity 7 лет назад +342

    The "everything happens for a reason" people need to watch this video.

    • @lifewitholga_
      @lifewitholga_ 7 лет назад +2

      GuildOfCalamity 😂

    • @katerinam1020
      @katerinam1020 7 лет назад +52

      I don't think the 'everything happens for a reason' people have anything to do with this. They do not have that motto because they believe (or not) in coincidences and stuff. It's about how every situation can be beneficial.

    • @HenleyPhoenix
      @HenleyPhoenix 7 лет назад +16

      GuildOfCalamity actually, I believe both in fate and logic. However, life itself is magical, why take all that magic away? After all, not everything can be perfectly explained. I believe in fate yet my intuition with this question was spot on, that was before I did the long math.
      Edited to make my point clearer.

    • @HenleyPhoenix
      @HenleyPhoenix 7 лет назад +18

      GuildOfCalamity GuildOfCalamity and I also agree with Katerina, many of "the 'everything happens for a reason' people" don't necessarily equate this belief to fate but that every situation, fate or otherwise is beneficial or needed in some way. Your inability to open your mind to the thinking of others will be your downfall.

    • @MatthewAshworth
      @MatthewAshworth 7 лет назад +37

      But everything indeed does happen for a reason. It's cause and effect. Every occurrence has been caused by all the necessary factors to make it possible, and this occurrence in turn will become one of the factors for any other occurrences that will follow up.

  • @ella5930
    @ella5930 4 года назад +36

    Reads the title: Haha jokes on u I’m a twin
    Two seconds in: nm

  • @blackandmentalhealth2936
    @blackandmentalhealth2936 4 года назад +58

    My college roommates and I all had the same birthday, born the same year and all three of us was hours apart.
    Edit: Also I have a best friend, she and her brother are born on the same day but a year apart. Lol

    • @Arti_Shovelhead
      @Arti_Shovelhead 4 года назад +1

      Again wow...3 the same year, roommates, and within hours...when you consider that people vary more in ages, in college, it seems as if the probability of the same year would decrease... but I'm no statistician.

    • @TheAtreyeeShill
      @TheAtreyeeShill 3 года назад +1

      Woah🤐

    • @nanetteestonina5480
      @nanetteestonina5480 3 года назад +1

      Are you still friends with your roommates though?

  • @salankritagogoi7212
    @salankritagogoi7212 3 года назад +19

    When I was in school, my school van had a total of 7 people and 3 out of them shared the same bday (Me, my younger brother and the van owner’s son) Surprisingly enough, 3 people in the van also shared the same name (my brother, the van owner’s son and another girl)
    Even more surprising is that both my brother and the van owner’s son are left handed and were the piano prodigies of the school😭😭
    It feels so weird till this day

  • @dominicgamboa2554
    @dominicgamboa2554 7 лет назад +71

    I'm always a sucker for collage and animation

  • @Lauren-cf6ek
    @Lauren-cf6ek 7 лет назад +68

    i watched this because yesterday was my birthday. turns out there was another girl with the same birthday as me in my class of 23 people. legit blew my mind

    • @soumya2972
      @soumya2972 4 года назад +3

      Gosh infact me too sharing my birthday with my classmate 😵 who just sits next to me. Can you imagine that.... It was like boom.. 99.9% chance out off 24 students 🤣

  • @taylordamidget9055
    @taylordamidget9055 7 лет назад +20

    wait they really re uploaded this just to change the less than symbols to more than symbols

  • @springlady8337
    @springlady8337 4 года назад +4

    I said 25 and it’s 23. I didn’t calculate at all. I just guessed. Isn’t intuition about feeling and instinct anyways? Why is this about math?

  • @ItsSolo
    @ItsSolo 3 года назад +4

    Why did I just sit here and watch this

  • @TTiger997
    @TTiger997 7 лет назад +18

    3:32
    That moment when TED-Ed starts to summon Satan with math

  • @kingarmish
    @kingarmish 7 лет назад +71

    I just crack an egg on my forehead rather than on pan after watching this...
    Help Me...😨😨😨

    • @wotchadave
      @wotchadave 6 лет назад +4

      silly, now you have egg on your face

    • @lplache
      @lplache 5 лет назад +6

      King Armish I read that as “I just crack my forehead on a pan rather than an egg” 😆 😂

  • @nyrajacob30
    @nyrajacob30 3 года назад +15

    TED-Ed : Try calculating the possibilities of people in your group having the same birthday as you.
    Me : I can just ask my friends you know
    TED-Ed : I-

  • @soumya2972
    @soumya2972 4 года назад +1

    GOSH READING COMMENTS BELOW..
    OF PEOPLE SAYING 😵😂.
    GETTING SURPRISED.. THAT THE VIDEO WAS UPLOADED IN MY BIRTHDAY..
    I'M LIKE :- ʅʕ•ᴥ•ʔʃ ??
    Seriously they are sharing their birthday...😂
    But second thoughts comes in my mind what if we make a group of people having same birthday date in same month it will be a 😂... 100% chances..of sharing birthday party and guess what...😂non of them would get high priority on their own birthday...🤣
    Lol !

  • @lxxy05
    @lxxy05 7 лет назад +20

    i love how this was uploaded on my birthday

  • @MrMKI-ux2sk
    @MrMKI-ux2sk 7 лет назад +53

    This is a common question we get in IIT-JEE

    • @ishitaagrawal4459
      @ishitaagrawal4459 4 года назад

      That's exactly what I thought during the video

    • @viscinating5896
      @viscinating5896 4 года назад

      U mean jee mains and advanced

    • @leonkirk8327
      @leonkirk8327 4 года назад

      I'm like twelve but whats IIT-JEE

    • @RagnarLothbrok-n2h
      @RagnarLothbrok-n2h 3 года назад +1

      @@leonkirk8327 ,it is the most difficult engineering entrance exam in India

  • @leomaple6868
    @leomaple6868 7 лет назад +9

    I love the visuals on this episode so much! And happy birthday to everyone, everyday, bc my intuition tells me that at least one who reads the comments has birthday

  • @hrydaygoyal3268
    @hrydaygoyal3268 3 года назад +6

    Disclaimer: People having diabetes should avoid watching this video

  • @dimps8574
    @dimps8574 4 года назад +7

    imagine having 2 friends on the same birthday how will you go to both of their birthdays. ;c
    and yes my friends have the same bday.

  • @williamkyburz
    @williamkyburz 7 лет назад +7

    I've asked a few people in my life about this question. I believe the reason they don't come close is not one of intuition, but misunderstanding the question. They seem to "fix" a date in their minds, i.e. their birthday, and ask a different question, "How many would it take to have my birthday?" Great question!

  • @kunjika
    @kunjika 7 лет назад +16

    And it still took me 20 years to bump into someone. Sometimes coincidences ARE as coincidental as they seem :P

    • @AbhimanyuSinghal1
      @AbhimanyuSinghal1 7 лет назад

      Who be that?

    • @kunjika
      @kunjika 7 лет назад

      You of course lol :P

    • @319mcg
      @319mcg 7 лет назад +1

      Is it in February?

    • @kunjika
      @kunjika 7 лет назад

      Kyla Renee Yes. February + 7 :P

    • @ainzoshle457
      @ainzoshle457 4 года назад +1

      Kunjika Prasai Fun Fact : The least popular birth month is January-February.

  • @msfred3209
    @msfred3209 5 лет назад +9

    Today is my birthday and nobody celebrated it with me. No family or friends. Then I ended up looking at birthday videos just to spite myself. Hahaha

    • @fz1792
      @fz1792 3 года назад +2

      I'll wish you then
      "Happy Birthday Dear"
      "May you have many more"
      Eat lots of sweets🍭🍬🍭🍬

    • @msfred3209
      @msfred3209 3 года назад

      @@fz1792 Thank youu! I did eat sweets a year ago. Another birthday of mine has passed and this time it was different. It just shows that you must held on so you're there for a changed future. 💜

    • @fa90lq
      @fa90lq 3 года назад +1

      Happy belated birthday

    • @starlet494
      @starlet494 3 года назад

      Happiest birthday to u 🎉🎉🎉🎉🎉🎉🎉🎉

  • @mahdimalekzadeh6410
    @mahdimalekzadeh6410 3 года назад +6

    *In college I shared a room with SIX of my friends and TWO of them had the same birthday.*
    I was wondering the odds and thought it's almost impossible but thank to you I can understand it better now.

    • @fos1451
      @fos1451 3 года назад

      If you're wondering, the probability is 5.6%

  • @popn6189
    @popn6189 4 года назад +1

    Am I the only one thats kinda scared of the edits?

  • @Iavenderhazes
    @Iavenderhazes 5 лет назад +11

    In my 5th grade class there were not 1, not 2, but 3 people with the exact same birthday!! (November 7th)

    • @ultraviolet.catastrophe
      @ultraviolet.catastrophe 4 года назад

      That's amazing because that's so rare! In a class of 30 students, the probability that exactly three of them share a birthday is 1.05%. In a class of 50 students, the probability drops to a mere 0.58%. In a class of 60 students, it drops even further to 0.21%. In a class of 100, the value is just 0.00007%.

    • @mikescholer1995
      @mikescholer1995 4 года назад +2

      @@ultraviolet.catastrophe shouldnt the probability get higher with more people getting involved? :D

    • @ultraviolet.catastrophe
      @ultraviolet.catastrophe 4 года назад +3

      @@mikescholer1995 That's a very good question. The answer is no. It's a counter-intuitive problem, that's why it seems the probability should get higher when more people are involved. In reality, the probability decreases because we are dealing with "exactly three people" and not "three people or more". Think of a football stadium. Or is it soccer? Whatever. The stadium has 100,000 people in attendance. What is the probability that JUST THREE PEOPLE have January 1st as their birthday? Which is to say, NONE of the other 99,997 people have Jan 1st as their birthday? Basically 0%. Allow me to be daring and claim, "that can never happen." I hope I have clarified things for you. Remember, we are interested in a scenario of EXACTLY THREE people and not THREE OR MORE.

    • @mikescholer1995
      @mikescholer1995 4 года назад +2

      @@ultraviolet.catastrophe Ah i was thinking about 3 or more thats why i was irritated :D
      Thanks for clearing that up!

    • @Anonymous-eo2er
      @Anonymous-eo2er 4 года назад

      There was 4 people (including me and my best friend) with the same birthday out of around 200 people. July 27th. My brothers birthday is July 28th so he was almost the fifth

  • @ajwehri
    @ajwehri 7 лет назад +6

    My math teacher proposed this same question to us, and I said that is was very unlikely. I was very shocked when another girl in my class had the same birthday as me.

  • @JadeTran1
    @JadeTran1 4 года назад +6

    I’ve never been a fan of math, but this video explains combination quite well! Really easy to understand 👌

  • @HemisphericLyric
    @HemisphericLyric 11 месяцев назад

    I have 23 people in my class (including me) and I share a birthday with one of them.

  • @jdschouhan14
    @jdschouhan14 4 года назад +4

    I am sure That the editing of the video took more time than the calculations

  • @muskanjaitly3813
    @muskanjaitly3813 7 лет назад +8

    We looked at this in my data management class! Loved the video because as someone who dislikes math more than anything in the world, this video was really well done and gave a great insightful explanation!

  • @laraamin798
    @laraamin798 7 лет назад +34

    Any January babies? :-)

  • @drshivraj5273
    @drshivraj5273 7 лет назад +37

    Lets check the probability. Comment if your birthday is in March.

  • @MikePouch
    @MikePouch Год назад +1

    I build a sheet in Excel to randomly generate 23 numbers between 1 and 365, with an alert whenever there was a match. I ran it 70 times and got an even 35:35 match/no match. Wild!!

  • @SyncJr
    @SyncJr 3 года назад +4

    Ya’ll not gonna believe me, but I legit thought “Like... 20 people?” When he asked the question at the beginning. So I’m not even one minute in and I already won. I am the stats king.

  • @dipperd9377
    @dipperd9377 7 лет назад +14

    love this vid

  • @breesevere
    @breesevere 7 лет назад +19

    This animation is impressive! Well done.

  • @martaskorupa6222
    @martaskorupa6222 4 года назад +6

    funny how during a school exchange i was matched with a person born on the exact same day as me :)

  • @lipstickprincess1
    @lipstickprincess1 2 года назад +1

    I only personally know one person born on April 1st.
    I love April Fool’s Day 😃🎂😘
    My birthday 🥰🥰🥰

  • @Shizoomz
    @Shizoomz 4 года назад +1

    In my elementary class, I shared my birthday AND birth hospital with 3 other people. Crazy

  • @luchiaseeds
    @luchiaseeds 4 года назад +4

    In my class of 25 people, we have 2 pairs with the same birthday... Huh

  • @jajabor2942
    @jajabor2942 3 года назад +4

    The question was "how big a group has to be", so I expected we'll find that size from scratch. But the video "picks" 23 as the size already and then explains how!

    • @cellocoversimprov5660
      @cellocoversimprov5660 3 года назад

      Solving for the number is a little bit tedious and not that interesting. I feel like the point of the video is to show that it's counterintuitive, not to work through an equation

  • @jogrejda8924
    @jogrejda8924 7 лет назад +5

    Hey everyone it's actually my birthday today I found this in my feed and started laughing really hard😋

  • @asterisque9252
    @asterisque9252 2 года назад +1

    The only person i share my birthday with (not counting Ronald Weasley since he's fictional) is Justin Beiber. I've never heard his songs too
    And knowing around a 100-200 people or so, with none of them sharing the same birthday, i can see why our intuition can be wrong, sort of.

  • @Ellie_S
    @Ellie_S 2 года назад +1

    i actually have a girl, in my class of 28 students, who shares the same birthday with me & we're not related. We're both born on the 24th... of January, which i've heard is kinda uncommon too :>

  • @kottonkandy0962
    @kottonkandy0962 6 лет назад +3

    Well, he never said that there weren't any triplets, quadruplets, quintuplets, sextuplets, septuplets, or octuplets, so...

  • @bengisuturkekul
    @bengisuturkekul 4 года назад +15

    I guessed 20 people before you even said "the number is suprisingly low" am i genius

  • @britbyars
    @britbyars 4 года назад +6

    I don’t think my intuition is wrong. I think that I don’t have the needed math skills to be able to come up with the answer. I need more education. Nothing to do with my intuition.

    • @sunmarsh
      @sunmarsh 4 года назад +1

      This is high school mathematics...

    • @kapengmainit286
      @kapengmainit286 4 года назад

      Nah, I have the math skills to understand this but when I first heard of it, I was surprised. I thought it's just a coincidence that there's always atleast 2 person I know with the same birthday whenever I go.

  • @youtubesus3930
    @youtubesus3930 3 года назад +1

    fun fact : 8B people around the world celebrate their birthdays in just 12 months
    btw the animation is epic

  • @hugonabais3875
    @hugonabais3875 5 лет назад +1

    I was 18 years in school had 7 classes of 25 students I knew everyone birthday's and I never had two people having the same birthday. I have two daughters that are in class now around 25 students and none of them have two people having the same birthday. This 50 % thing doesn't add up... Sorry

  • @thefrenchpoet3160
    @thefrenchpoet3160 7 лет назад +5

    So what is the odds that out of the 1022 comments, that 2 of us share a birthday

    • @sweetgirl070707
      @sweetgirl070707 7 лет назад +1

      Sky M 100%

    • @319mcg
      @319mcg 7 лет назад

      I'm searching for mine, Feb 10, not seeing it

    • @fos1451
      @fos1451 5 лет назад

      Anhel Rajikova well it is not 100% for 1 people but 100% for someone in the group you still have only 0.003% that people have the same birthday as you

  • @phoenixwright3069
    @phoenixwright3069 5 лет назад +4

    **waits patiently for that comment that says, “This video was uploaded on my birthday!”**

  • @user_8983
    @user_8983 4 года назад +7

    I absolutely love these editing skillz.

  • @jhonyaraujo1879
    @jhonyaraujo1879 4 года назад +1

    I am not sure this is right, but if you think about it then, a group of 366 people would already have a 100% chance of sharing a birthday, right? Cause even if each one of the 365 was born in different days of the year, the 366th would have to have been born on a day already occupied.

  • @aidenhall5301
    @aidenhall5301 2 года назад +1

    This problem inspired me to make a whole Java program that makes runs these simulations so I don’t have to guess or even do much math really. Using just the law of large numbers and a lot of computing power, I can let the computer do all the work.

  • @brookeswanson9077
    @brookeswanson9077 4 года назад +8

    When you’re born on a leap day so the probability of you having the same birthday as someone else in the room is 0 coz according to the video your birthday doesn’t count 😢

  • @marsish4963
    @marsish4963 4 года назад +4

    This was recommended on my birthday

  • @RacilAtutubo
    @RacilAtutubo 6 лет назад +4

    I remember my classmate who were beside me when we were in an immersion. He just randomly blurted out that his birthday is Dec6, same as mine. 😂

  • @sarahdrummond5334
    @sarahdrummond5334 3 года назад +1

    anyone here born on august 5? i share a birthday with my dad but that’s all i know of.
    happy birthday for tomorrow if we share a birthday 💕

  • @net_lag
    @net_lag 3 года назад +1

    You guys forgetting the fact that they meant any two people to share the same birthday, not with yours in particular.

  • @camillajones7463
    @camillajones7463 7 лет назад +4

    I love TED, and I really trust their videos. But I just can't really believe this. It just seems so unlikely to me.

    • @HoratioAccel
      @HoratioAccel 7 лет назад

      Camilla Jones I bet you did well in calculus

    • @JMan360
      @JMan360 5 лет назад

      Believe it

    • @littlefishbigmountain
      @littlefishbigmountain 4 года назад

      Aadhya Tripathi
      Yeah, like nine months after major holidays and June (where many people get married) for example, aha

    • @littlefishbigmountain
      @littlefishbigmountain 4 года назад

      The thing is, if you’re looking at it as someone sharing a birthday with _you_ instead of any pairing then the odds go down dramatically because the pairings are cut down to only those that connect to you

  • @diamondust2054
    @diamondust2054 4 года назад +3

    that means that in a group on 90 people there’s over 100% chance of two people having the same birthday, which doesn’t seem right... but i might be wrong

    • @meiy.1961
      @meiy.1961 4 года назад +3

      You never actually hit 100% or go over it, you just get very close to 100% from below. It's because you're multiplying 365/365 (or 1 or 100%) by ever decreasing values smaller than 1 (0.99 or 0.98...etc).
      1*0.99 < 1
      1*0.99*0.98 < 1*0.99
      1*0.99*0.98*0.97 < 1*0.99*0.98
      Etc
      So the more you multiply (the more people you add to the group), the smaller the number gets. 1 minus a very small number (chance that nobody finds a pair in a group of 90) is still less than 1. Therefore you cannot get a probability over 100%.

    • @diamondust2054
      @diamondust2054 4 года назад

      Mei Y. oh okay, thank you!

    • @felixalmblad5572
      @felixalmblad5572 3 года назад

      @@meiy.1961 you go up to 100% whit 366 people

    • @felixalmblad5572
      @felixalmblad5572 3 года назад

      with

  • @twitzmixx8374
    @twitzmixx8374 3 года назад +5

    Everyone: Talking about the math
    Me: Getting creeped by the smiling heads on the sticks

  • @eutrophication845
    @eutrophication845 3 года назад +1

    And thats why i have problem with probability in math, it doesnt feel realistic

  • @jdh9419
    @jdh9419 2 месяца назад +1

    Easy way to ensure at least one person in your group has a birthday that is the same as another: Bring at least 366 people in your group

  • @tonistaak
    @tonistaak 5 лет назад +4

    This applies to death day also😂

    • @soumya2972
      @soumya2972 4 года назад

      Exactly 🤣🤣🤣🤣

    • @lesfrog649
      @lesfrog649 4 года назад

      So you're saying that there's more than a 50% chance that there are two people in my class who will die at the same day?...
      Alright you little shits who's dying with me

    • @chloema9616
      @chloema9616 3 года назад

      Yo anyone shares the coffin with me 😂😂

  • @ivan2951
    @ivan2951 5 лет назад +3

    RUclips's recommendation wants to remind me that it is my birthday today.

  • @x_x__o_x
    @x_x__o_x 4 года назад +3

    I share the same birthday with my brother. He’s three years older than me-

  • @tonistaak
    @tonistaak 5 лет назад +1

    Can anybody calculate minimum people required so that 2 people have 50% chance of dying same year,Given that most of us won't live more than 100 years. Just for fun 😂

    • @tonistaak
      @tonistaak 5 лет назад

      So for people born in same year,2 people out of 12 people have more than 50% chance of dying in same year.

  • @sorrynotsorry8224
    @sorrynotsorry8224 Год назад +1

    My initial guess would have been around the square root of 365, which isn't far off at 19.

    • @chillidog1988
      @chillidog1988 Год назад

      I thought so similarly, but I can't figure out why that's the first thing I thought of :P

  • @ImBeelii
    @ImBeelii 7 лет назад +9

    My birthday is the 4th of may xDD

  • @johnyoder61
    @johnyoder61 7 лет назад +5

    haha well its 100 percent chance when its 366 (no twins or leap year

    • @ectoOLDACC
      @ectoOLDACC 6 лет назад +1

      *)
      (Sorry, I'm one of those people that get annoyed about those errors)

    • @fos1451
      @fos1451 5 лет назад

      John Yoder not the same birthday if they use different calendars

  • @andrej2435
    @andrej2435 7 лет назад +4

    its interesting also m bday is tomorow !
    🍰🎉🎉

  • @redhot663
    @redhot663 3 года назад +1

    But if winning the lottery twice is not as unlikely as we think, why is it so unlikely to win it once?

  • @logeshwariarumugam5894
    @logeshwariarumugam5894 3 года назад +1

    Its strange, this video got recommended on my birthday :):)

  • @theomegabros.5366
    @theomegabros.5366 6 лет назад +3

    Ironic combats hahaha how ironic

  • @samueldullaart
    @samueldullaart 7 лет назад +6

    I estimated 20 to 30 people yet he automatically assumes my intuition was wrong :S