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 red, white or blue .......

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

Answer 1

The correct option is D $\frac{4}{5}$

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

Number of red balls, 10

Number of white balls, 30

Number of blue balls, 20

Hence the number of favourable outcomes for getting a red, white or blue ball is, $n\left(E\right)=10+30+20=60$

Hence the probability of a ball drawn is red, white or blue is, $\frac{n\left(E\right)}{n\left(S\right)}=\frac{60}{75}=\frac{4}{5}$