Question

A bag contains 5 white balls, 4 red balls and 3 green balls. A ball is drawn at random. Find the probability that it is a ball which is not green.

• A. $\frac{3}{5}$
• B. $\frac{3}{4}$
• C. $\frac{2}{5}$
• D. $\frac{1}{5}$

Answer 1

The correct option is B $\frac{3}{4}$

Total number of balls in the bag $5+4+3=12$.

We denote the event of getting a red ball as $R$, that of getting a green ball $G$, that of getting a colored ball as $C$ and that of getting a ball not green as $\overline{G}$ or not $G$.

There are $5+4=9$ balls which are not green i.e. white or red, so there are $9$ outcomes that favor the event, not $G$.

$P\left(NotGreen\right)=\frac{\text{Number of outcomes which favour No Green}}{12}$

Therefore, $P($not $G)=\frac{9}{12}=\frac{3}{4}$