1. The problem statement, all variables and given/known data An urn contains one white chip and a second chip that is equally likely to be white or black. A chip is drawn at random and returned to the urn. Then a second chip is drawn. What is the probability that a white appears on the second draw given that a white appeared on the first draw. 2. Relevant equations 3. The attempt at a solution I am trying to use the equation P(white2 | white 1) = p(white2 and white 1) / P(white1) The back of the book says the answer is 5/6. I am fairly sure that P(white1) is (1/2)(2/2) + (1/2)(1/2) or .75 So that would make p(white2 and white1) to be 5/8 which I can't for the life of me see why. Any ideas on how to do this? The examples we work out in class are so elementary and I get bored. The problems assigned for homework as very hard (or at least this seems much much harder). Thanks for any help!