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 coloured ball.

• A. $\frac{1}{12}$
• B. $\frac{7}{12}$
• C. $\frac{5}{12}$
• D. $\frac{1}{3}$

Answer 1

Answer: (B)

$\frac{7}{12}$

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 $4+3=7$ coloured balls, i.e. either red or green.

So, $7$ outcomes favour the event $C$.

$P\left(C\right)=\frac{\text{Number of outcomes which favour C}}{12}$

$\therefore P\left(C\right)=\frac{7}{12}$