GMATPrepNow wrote:
A ball is randomly selected from a box containing white balls and black balls only. If the probability of randomly selecting a white ball is 4/5, how many white balls must be added to the box so that the probability of randomly drawing a white ball is 7/8?
(1) The ratio of white balls to black balls is 4:1
(2) There are 27 more white balls than black balls
* kudos for all correct solutions
Tricky
You don't need statement 1 because it is already implied in the question stem
B
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