June 19th, 2014, 8:11 am
HiI was recently asked this question in a phone interview and I am still not sure why the answer is what the interviewer said it was.Here is the question"You have two bags. One bag has 3 white and 1 black ball and the other bag has 1 white and 3 black balls. You select one of the bags at random (bags have equal probability of being selected) and pick a ball. This ball is black. You then replace the ball. What is the probability that if you pick a ball again it is black."To be the first and second events are independent and therefore have the same probability of 1/2. The interviewer, however, said they are not and the second event has higher probability than the first. Can someone explain why?Thanksswmi