There are 7 black and 3 White ball in one bag and 4 black and 6 White ball in another bag . A die is tossed and if it shows number 1 or 2 two balls are drawn from the first bag and if 3,4,5 or 6 is shown on the die two balls are drawn from the second bag. If both the balls drawn are black. find the probability that they come from the second bag.
