Answer
$P(E)=\frac{12}{365}\approx0.0329$.
It means that, if we randomly select 3650 people, we would expect that the number of people that have a birthday on the 1st day of a month is about 120.
Work Step by Step
Event = "birthday on the 1st day of a month" = {Jan 1, Feb 1, Mar 1, Apr 1, May 1, Jun 1, Jul, 1, Aug 1, Sep 1, Oct 1, Nov 1, Dec 1}. So, $N(E) = 12$.
One year = 365 days, so $N(S) = 365$.
Using the Classical Method:
$P(E)=\frac{N(E)}{N(S)}=\frac{12}{365}\approx0.0329$
