question_answer 81)

How many times must a man toss a fair coin so that the probability of having atleast one head is more than 90%. 

Answer:

Let required number of trials are n.       Let x is the number of heads, then x has the binomial distribution with number of trials = n,       According to question, P(atleast one head) >                                        ? (1)       Since  = 12, 2, 3, 4, 5, ?       Therefore n = 4, 5, 6?? will satisfy (1)                   Hence