Question
There are 4 red balls, 5 blue balls and 3 green balls in
a jar. 2 balls are drawn at random. Find the probability that both balls are either green or red.Solution
Given 4 red, 5 blue,3 green balls Total possible outcomes (selecting 2 out of 12 balls) = 12C2 = (12 × 11)/(2 × 1) = 66 ​Favorable outcomes (selecting 2 out of 4 red balls) = 4C2 = (4 × 3 × 2)/ (2 × 2 × 1) = 6 Favorable outcomes (selecting 2 out of 3 red balls) = 3C2 = (3 × 2)/ (2 × 1) = 3 => P(E) = (6 + 3)/66 = 9/66 = 3/22
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