Question
A bag contains 5 red, 4 blue and 3 green balls (12 balls
in total). Two balls are drawn at random without replacement. Find the probability that both balls drawn are of the same colour.Solution
Total ways to choose 2 balls from 12 = C(12, 2) = 66. Favourable cases: Both red: C(5, 2) = 10 Both blue: C(4, 2) = 6 Both green: C(3, 2) = 3 Total favourable = 10 + 6 + 3 = 19 Probability = 19 / 66.
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