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

Let us assume that, man tosses the coin n times. Thus, n tosses are the Bernoulli trials

Probability of getting head at the toss of the coin

Let us assume,

It is given in the question that,

Probability of getting at least one head >

1 – P (x = 0) > 0.9


Hence, the minimum value of n satisfying the given inequality = 4

The man have to toss the coin 4 or more times