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A bag contains 2 red, 3 green and 2 blue balls .Two balls are drawn at random. What is the probability that none of the balls drawn is blue?

A bag contains 2 red, 3 green and 2 blue balls .Two balls are drawn at random. What is the probability that none of the balls drawn is blue? Correct Answer 10/21

Total number of balls = (2 + 3 + 2) = 7 Let S be the sample space Then, n(S) = Number of ways of drawing 2 balls out of 7 n(S) = 7C2 n(S) = (7 × 6)/(2 × 1) n(S) = 21 Let E = Event of 2 balls, none of which is blue ∴ n(E) = Number of ways of drawing 2 balls out of (2 + 3) balls n(E) = 5C2 n(E) = (5 × 4)/(2 × 1) n(E) = 10 ∴P(E) = n(E)/n(S) = 10/21

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