Question

An unbiased coin is tossed 5 times. Suppose that a variable X is assigned the value k when k consecutive heads are obtained for k = 3, 4, 5 otherwise X takes the value -1. Then the expected value of X, is :

(1) 3/16

(2) - 3/16

(3) 1/8

(4) - 1/8

Answer 1

Answer is (3) 1/8

k = no. of times head occur consecutively now expected value is

Answer 2

Answer is (3) 1/8