The minimum number of times a fair coin needs to be tossed so that the probability of getting at least two heads is at least 0 . 96 , is

Step-by-step solution

P 2 + P 3 … ≥ 0 .96 1 - P 0 - P 1 ≥ 0 .96 1 - 0 .96 ≥ n C 0 1 2 n + n C 1 1 2 n ⇒ 0 .04 2 n ≥ 1 + n ⇒ 4 .2 n ≥ n + 1 100 ⇒ 2 n + 2 ≥ n + 1 100 As, 2 10 ≥ 900 ⇒ n = 8