Question

A bag contains 5 red, 8 black and 7 white balls. One ball is chosen at random. What is the probability that the chosen ball is black?
(a) $\frac{2}{3}$

(b) $\frac{2}{5}$

(c) $\frac{3}{5}$

(d) $\frac{1}{3}$

Answer 1

(b) $\frac{2}{5}$

Explanation:
Total number of balls in the bag = 5 + 8 + 7 = 20
Number of black balls = 8

Let E be the event that the chosen ball is black.

∴ Required probability = P(E) = $\frac{8}{20}=\frac{2}{5}$