Question

Assume the year to be ordinary consisting of 365 days. What is the probability that in a group of 2 people, both will have the same date of birth?

• A. $\frac{1}{365}$
• B. $\frac{1}{364}$
• C. $\frac{364}{365}$
• D. none of these

Answer 1

Answer: (A)

$\frac{1}{365}$

Given, The year to be of ordinary one which has $365$ days.

$\therefore$ The probability that $2$ people will have same birthday $=\frac{365}{365}\times \frac{1}{365}=\frac{1}{365}$

(Since the first person date can be selected 365 ways among 365 days,Probaility of selecting first person's birth date $=\frac{365}{365}$. But second person should have same date as first person. So, only one date can be selected which is same as first person. Therefore,the probability of selecting second person date $=\frac{1}{365}$)