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When posting questions, please use the spoiler function to hide the correct answer. This will allow others to attempt the question without seeing the final answer.Johnrohit wrote:In a bag of marbles, there are 3 red, 2 white, 5 blue. If bob takes 2 marbles out of the bag, What is the probability that he will have one white and one blue marble?(Assuming that Bob does not replace the marbles in the bag)
Answer- 2/9
Thanks!
rohit
Alternate approach:Johnrohit wrote:In a bag of marbles, there are 3 red, 2 white, 5 blue. If bob takes 2 marbles out of the bag, What is the probability that he will have one white and one blue marble?(Assuming that Bob does not replace the marbles in the bag)
thanks for the info.... I was following a comprehensive method!! ur and GMAT GURUS method r way better!! Thank u! Brent@GMATPrepNow wrote:When posting questions, please use the spoiler function to hide the correct answer. This will allow others to attempt the question without seeing the final answer.Johnrohit wrote:In a bag of marbles, there are 3 red, 2 white, 5 blue. If bob takes 2 marbles out of the bag, What is the probability that he will have one white and one blue marble?(Assuming that Bob does not replace the marbles in the bag)
Answer- 2/9
Thanks!
rohit
P(1 white and 1 blue) = P(1st is white and 2nd is blue OR 1st is blue and 2nd is white)
= [P(1st is white) x P(2nd is blue)] + [P(1st is blue) x P(2nd is white)]
= [2/10 x 5/9] + [5/10 x 2/9]
= [10/90] + [10/90]
= 20/90
= [spoiler]2/9[/spoiler]
Cheers,
Brent
