Homework Soursewhat is the probability that in a group of 20 randomly selec
what is the probability that in a group of 20 randomly selected students (from a current section of STA 9708 Statistics) 2 or more will be found to share the same birthday? Ignore leap years (like 2012)?
what is the probability that in a group of 20 randomly selected students (from a current section of STA 9708 Statistics) 2 or more will be found to share the same birthday? Ignore leap years (like 2012)?
what is the probability that in a group of 20 randomly selected students (from a current section of STA 9708 Statistics) 2 or more will be found to share the same birthday? Ignore leap years (like 2012)?
Solution
There are 365^20 ways to choose birthdays.
There are 365P20 ways so that no two have the same birthday.
As
P(2 or more with same birthday) = 1 - P(all birthdays unique)
Then
P(2 or more with same birthday) = 1 - 365P20 / (365^20)
= 0.588561616 [ANSWER]
