Question
Mon January 30, 2012 By:
 

a bag contains 5 red balls and some blue balls if the probability of deriving a blue ball is double than that of a red ball, find the number of blue balls in the bag

Expert Reply
Mon January 30, 2012
Let number of blue balls be b
Total number of balls = 5 + b
Probability of picking a red ball, P(R) = 5/(5 + b)
Probability of picking a blue ball, P(B) = b/(5 + b)
Given,        P(B) = 2 x P(R)
implies       5/(5 + b) =  2 {5 / (5 + b)}
Therefore,            b = 10
Number of blue balls in the bag = 10
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