Question

A jar contains 30 marbles, some are green and others are red. If a marble is drawn at random from the jar, the probability that it is green is $\frac{3}{5}$. Find the number of green balls in the jar. $\left[2\right]$

Answer 1

Here, total number of outcomes = 30
Let there be x green marbles.

Therefore favourable number of outcomes = x
$\therefore P\left(G\right)=\frac{x}{30}$ $\left[1mark\right]$

$ButP\left(G\right)=\frac{3}{5}$
$\Rightarrow \frac{x}{30}=\frac{3}{5}$
$\Rightarrow x=18$

Therefore number of green marbles are 18$\left[1mark\right]$