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 girl

Answer 1

Given number of boys$=30$ and number of girls$=25$

Total number of students $=30+25=55\therefore n\left(S\right)=55$

Let $B$ be the event of choosing a girl

$\therefore n\left(B\right)=25$

$\therefore P\left(B\right)=\frac{n\left(B\right)}{n\left(S\right)}=\frac{25}{55}$