Question
A bag contains 9 white balls, 6 black balls, and 3 green
balls. Two balls are drawn at random. Find the probability that the two balls are white.Solution
Number of ways of selecting two white balls = 9Câ‚‚
Total number of balls = 9 + 6 + 3 = 18
Number of ways of selecting two balls = 18 Câ‚‚
Probability = 9 C₂ ÷ 18 C₂ = (9 × 8) ÷ (18 × 17) = 72 ÷ 306 = 4/17
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