Question

A and B are friends. Ignoring the leap year, find the probability that both friends will have the same birthday? 

Answer 1

Out of the two friends, A's birthday can be any day of the year. Now, B's birthday can also be any day of 365 days in the year. 

We assume that these 365 outcomes are equally likely.  

P(A and B have the same birthday) 

= 1 – P(both have different birthdays) 

= `1 - 364/365`  ...[Using P(E') = 1 – P(E)] 

= `1/365`