OpenStudy (anonymous):

A plane is missing and is presumed to have equal probabilityof going down in any of three regions. If a plane is actually downin region i, let 1-αi denote the probability thatthe plane will be found upon search of the ith region, i=1,2,3.What is the conditional probability that the plane is in a) region 1, given that the search of region 1 wasunsuccessful b) region 2, given that the search of region 1 wasunsuccessful c) region 3, given that the search of region 2 wasunsuccessful