Question

An urn contain 4 white 2 green and 4 black balls. 3 balls are drawn at random. What is the probability that the drawn balls are (1) 3 white (2) 1 white and 2 green (3) one of each colour. Select the correct answer from above options

Answer 1

n(S) = (4 + 2 + 4)C3 = 10C3 = 10 × 9 × 8 3 × 2 × 1 10 = 120 (1) Let A = 3 white balls ⇒ n(A) = 4C3 = 1 P(A) = n ( A ) n ( A ) n = 1 120 1 (2) Let B: 1 white or 2 green n(B) = 4C1 x 2C2 = 4 x 1= 4 (3) Let C1: one of each colour: n(B) = 4C1 x 2C1 x 4C1 = 4x2 x = 32.