Question

A fair coin is tossed three times. The random variable X is defined to be , where h is the number of flips that come up heads. For example, X(HHT) = 2 . What is E[X]? a 3/2 b 27/8 c 2 d 1

Answer 1

E[X] = 0(1/8) + 1(3/8) + 2(3/8) + 3(1/8)

= 3/8 + 6/8 + 3/8

= 12/8

= 3/2

The correct answer is A.