Question

A bag contains 6 red balls and some blue balls. If the probability of drawing a blue ball from the bag is twice that of a red ball, find the number of blue balls in the bag.

Answer 1

Let the number of blue balls in the beg be x.
Then, total number of balls = (5+x).
Given , P(a blue ball) `=3 xx ` P(a red ball)
` :. x/((5+x)) = 3 xx 5/((5+x)) rArr x = 15`.
Hence, the number of blue balls in the bag is 15.