Question

A company with n employees publishes an internal calendar, where each day lists the employees having a birthday that day. What is the probability there is at least one day in a year when nobody has a birthday?

Answer 1

Answer: $1-(\frac{364}{365})^n$

Step-by-step explanation:

Binomial probability formula :-

$P(x)=^nC_xp^x(1-p)^x$, where P(x) is the probability of getting success in x trials, n is the total number of trials and p is the probability of getting success in each trial.

We assume that the total number of days in a particular year are 365.

Then , the probability for each employee to have birthday on a certain day :

$p=\dfrac{1}{365}$

Given : The number of employee in the company = n

Then, the probability there is at least one day in a year when nobody has a birthday is given by :-

$P(x\geq1)=1-P(x$

Hence, the probability there is at least one day in a year when nobody has a birthday =$1-(\frac{364}{365})^n$