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Question
How many times must a man toss a fair coin so that the probability of having at least one head is more than 90%?
Solution
Let the man toss the coin n times. The n tosses are n Bernoulli trials.
Probability (p) of getting a head at the toss of a coin is `1/2`
It is given that,
P (getting at least one head) > `90/100`
P (x ≥ 1) > 0.9
⇒ 1 − P (x = 0) > 0.9
The minimum value of n that satisfies the given inequality is 4.
Thus, the man should toss the coin 4 or more than 4 times.
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