Question
A bag contains 4 red and 3 blue balls. Two balls are
drawn at random without replacement. Find the probability that both balls are of the same colour.Solution
Total balls = 4 + 3 = 7 Total ways to choose 2 = 7C2 = 21 Favourable cases: Both red: 4C2 = 6 Both blue: 3C2 = 3 Total favourable = 6 + 3 = 9 Probability = 9 / 21 = 3 / 7 Answer: 3/7.
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