Question
A bag contains 4 green balls, 11 red balls, and 3 white
balls. Two balls are drawn at random. Find the probability that the two balls are red.Solution
Number of ways of selecting two red balls = 11 Câ‚‚
Total number of balls = 4 + 11 + 3 = 18
Number of ways of selecting two balls = 18 Câ‚‚
Probability = 11 C₂ ÷ 18 C₂ = (11 × 10) ÷ (18 × 17) = 110 ÷ 306 = 11/31
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