A bag contains 8 red, 2 black and 5 white balls.
Question:

A bag contains 8 red, 2 black and 5 white balls. One ball is drawn at random. What is the probability that the ball drawn is not black?

(a) $\frac{18}{15}$

(b) $\frac{2}{15}$

(c) $\frac{13}{15}$

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

Solution:

(c) $\frac{13}{15}$

Explanation:
Total possible outcomes = Total number of balls

= ( 8 + 2 + 5) = 15

Total number of non-black balls = (8 + 5) = 13

$\therefore P$ (getting a ball that is not black) $=\frac{13}{15}$