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What is the probability that two people in a group have the same birthday?
a 50 percent
You can test it and see mathematical probability in action! The birthday paradox, also known as the birthday problem, states that in a random group of 23 people, there is about a 50 percent chance that two people have the same birthday.
How many people on average have the same birthday as you?
That would be a much smaller number (but still pretty giant). So, what’s the verdict? The number of people with the same date of birth as you is somewhere around 20.8 million. Yes, you share your big day with millions of people.
How many couples share the same birthday?
It’s certainly a rarity. Statistically speaking, with 365 days in a year, there’s a . 27 percent chance of any two people sharing the same calendar date as birthdays .
How common is it to share a birthday?
One person has a 1/365 chance of meeting someone with the same birthday. Two people have a 1/183 chance of meeting someone with the same birthday. But! Those two people might also have the same birthday, right, so you have to add odds of 1/365 for that.
In a group of 23 people, the probability of a shared birthday exceeds 50\%, while a group of 70 has a 99.9\% chance of a shared birthday. (By the pigeonhole principle, the probability reaches 100\% when the number of people reaches 367, since there are only 366 possible birthdays, including February 29.)
How many people in a group of N have the same birthday?
The problem is to compute an approximate probability that in a group of n people at least two have the same birthday. For simplicity, variations in the distribution, such as leap years, twins, seasonal, or weekday variations are disregarded, and it is assumed that all 365 possible birthdays are equally likely.
How many people do you need to share a birthday?
In this case, it can be shown that the number of people required to reach the 50 percent threshold is 23 or fewer. For example, if half the people were born on one day and the other half on another day, then any two people would have a 50 percent chance of sharing a birthday.
What is the general birthday problem in statistics?
The generalized birthday problem. Given a year with d days, the generalized birthday problem asks for the minimal number n(d) such that, in a set of n randomly chosen people, the probability of a birthday coincidence is at least 50\%.