Question

From a vessel containing 3 white and 5 black balls, 4 balls are transferred into an empty vessel. from this vessel a ball is drawn and is found to be white .what is the probability that out of four balls transferred 3 are white and 1 is black

Answer 1

I would find all the possible first draws (4B 0W), (3B 1W), (2B 2W), (1B 3W) and give each of them a probability of happening. Then, from each of those nodes, find the probability that a white is drawn from them. Multiply the two probabilities together in each case. Then make a fractionprobability of drawing a white from 1B 3Wsum of all probabilities that led to drawing a white ball