Question
A bag contains 3 black balls, 12 blue balls, and 3
yellow balls. Two balls are drawn at random. Find the probability that the two balls are blue.Solution
Number of ways of selecting two blue balls = 12 Cβ
Total number of balls = 3 + 12 + 3 = 18
Number of ways of selecting two balls = 18 Cβ
Probability = 12 Cβ Γ· 18 Cβ = (12 Γ 11) Γ· (18 Γ 17) = 132 Γ· 306 = 22/51
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