A high diver dives into a pool. He enters the pool 4 feet from the edge of the pool and resurfaces 7 feet from the edge. If at 5 feet from the edge of the pool he is 6 feet below the water, what is the lowest point at which the diver reached?

There are three bags: a (contains 2 white and 4 red balls), b (8 white, 4 red) and c (1 white 3 red). you select one ball at random from each bag, observe that exactly two are white, but forget which ball came from which bag. what is the probability that you selected a white ball from bag a?