# Dating someone with the same birthday

A consequence of this is that the pool of people you know from the exact same ages is by guesstimation a factor of 5 bigger than the expected value, if $age If it's an event specified before the fact, you can simply break it down: The chance that your boyfriend was born the same year as you is actually very high (especially given many situations tend to bring people of very similar age together); it's a very difficult probability to calculate, though, without data.If you had that probability, P(Same day and same year) = P(Same year) $\times$ P(Same day|same year).It will also list all the possible name combinations if you really want to! I’ll be the first to admit I haven’t used this in class for the main reason that with 25 students in a class, the odds are a bit over 50/50 that this experiment will work.A second reason is that the above math is over simplified to be somewhat understandable.Same Birthday Odds It stands to reason that same birthday odds for one person meeting another are 1/365 (365 days in the year and your birthday is on one of them).But consider this: If you get a group of 30 people together, two of them will almost definitely have the same birthday. There were 30 students in my undergrad statistics class and the professor said the odds of two of us having the same birthday were very high. We’re talking about every student having those odds.Seeing as the odds are 1/365 that any two students will match birthdays and there are 3 possible matches, it’s no surprise that two of those students share the same birthday.(Use the combinations calculator to figure the combinations out.

Visit Stack Exchange Cross Validated is a question and answer site for people interested in statistics, machine learning, data analysis, data mining, and data visualization. Sign up to join this community I share the same birthdate as my boyfriend, same date but also same year, our births are seperated by merely 5 hours or so.Twenty nine of us meeting someone with the same birthday: 1/12.Those are pretty good odds, but not high enough to account for all those coincidences. The odds are actually much higher (over 100 percent for a class of 30).It’s like if I had a 1/10 chance of winning the lottery and I meet another person who also has a 1/10 chance of winning the lottery, then combined we have a 2/10 chance of winning the lottery.The odds of a “coincidence” increases with each person: Me meeting a person with the same birthday: 1/365 Me and one other friend meeting someone with the same birthday: 1/(365/2) = 183 Three of us meeting someone with the same birthday: 1/(365/3) = 1/122 …