Question

A ball is drawn at random from a box containing 10 red, 30 white, 20 blue and 15 orange marbles. The probability of a ball drawn is neither red nor blue is.....

• A. $\frac{1}{3}$
• B. $\frac{3}{5}$
• C. $\frac{11}{15}$
• D. $\frac{2}{5}$

Answer 1

The correct option is B $\frac{3}{5}$

Total number of balls in the box, $n\left(S\right)=10+30+20+15=75$

Number of red balls, 10

Number of blue balls, 20

Hence the number of favourable outcomes for getting neither red nor blue ball is, $n\left(E\right)=75-10-20=45$

Hence the probability of a ball drawn is neither red nor blue is, $\frac{n\left(E\right)}{n\left(S\right)}=\frac{45}{75}=\frac{3}{5}$