Question

A box contains 3 black and 7 white balls. A ball is picked up at random, two more balls of the same color are added to the box. A ball is drawn again and two more balls of the same color are added to the box. Now a ball is chosen from the box and found to be black. What is the probability that the first ball drawn is white?

Answer 1

favourable outcomes = 7

total possible outcomes = 10

p ( getting a white ball) = 7/10......

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