一道英文数学概率题
A box contains 4 black cubes and 6 white cubes.A cube is drawn from the box.Its colour noted and a cube of the other colour is then added to the box.A second cube is then drawn.
(a).If both cubes are of the same colour,what is the probability that both cubes were in fact white?
(b).The first ball is replaced before the second ball is added to the box.What is the probability that both cubes were white given that both cubes were of the same colour?