Question
A bag contains six green balls, four red balls and two
yellow balls. Two balls are drawn at random, what is the probability that both are of the same colour?Solution
Two balls can be drawn from 12 balls in 12 C 2  ways.
The number of ways of drawing two balls of the same
Colour =Â 6 C 2 Â +Â 4 C 2 Â +Â 2 C 2 Â = 15 + 6 + 1
∴ The required probability = 22/ 12 C 2  = (22*2)/(12*11) = 1/3
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