A coin is tossed 3 times. Find the probability that all the 3 are heads
(A) if it is known that the first is heads
(B) if it is known that the first 2 are heads
(C) if it is known that the 2 of them are heads
(A) if it is known that the first is heads
(B) if it is known that the first 2 are heads
(C) if it is known that the 2 of them are heads