Past papers › WAEC · 2021 · May/June · General Maths · Paper 1 › Question 45 Question WAEC General Maths 2021 Objective Probability Probability
WAEC 2021 · Paper 1 · Q45 A box contains 40 identical balls of which 10 are red and 12 are blue. A ball is selected at random. What is the probability that it is neither red nor blue?
A 9 20 \frac{9}{20} 20 9 B 3 10 \frac{3}{10} 10 3 C 1 4 \frac14 4 1 D 11 20 \frac{11}{20} 20 11
Worked solution (try it first) Red and blue together are
10 + 12 = 22 10 + 12 = 22 10 + 12 = 22 balls.
Neither red nor blue leaves
40 − 22 = 18 40 - 22 = 18 40 − 22 = 18 balls.
So the probability is
18 40 = 9 20 \frac{18}{40} = \frac{9}{20} 40 18 = 20 9 , option A.
Watch out
22 40 = 11 20 \frac{22}{40} = \frac{11}{20} 40 22 = 20 11 Report a problem with this question