Question
A bag contains 19 white and some black balls. If the
probability of drawing a black ball from the bag is twice that of drawing a white ball, find the number of black balls in the bag.Solution
Given, Number of white balls = 19 Let x be the number of black balls. Total number of balls in the bag = 19 + x Also, the probability of drawing a black ball from the bag is twice that of drawing a white ball. ⇒ x/(19 + x) = 2[19/(19 + x)] ⇒ x = 38 Hence, the number of black balls in the bag = 38.
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