Question

There are $30$ boys and $25$ girls in a class. A student is chosen at random. Find the probability that the chosen student is a boy

Answer 1

Total number of students $=30+25=55\therefore n\left(S\right)=55$
Let $A$ be the event of choosing a boy
$\therefore n\left(A\right)=30$
$\therefore P\left(A\right)=\frac{n\left(A\right)}{n\left(S\right)}=\frac{30}{55}$