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(D) Let the coin be tossed $n$ times. Let $X$ be the number of heads obtained.$X$ follows a binomial distribution with parameters $n$ and $p = 1/2$.We

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None of these

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(D) Let the coin be tossed $n$ times. Let $X$ be the number of heads obtained.$X$ follows a binomial distribution with parameters $n$ and $p = 1/2$.We want $P(X \geqslant 1) \geqslant 0.8$.This is equivalent to $1 - P(X = 0) \geqslant 0.8$.$1 - (1/2)^n \geqslant 0.8$.$(1/2)^n \leqslant 0.2$.$(1/2)^n \leqslant 1/5$.$2^n \geqslant 5$.For $n = 1$,$2^1 = 2 For $n = 2$,$2^2 = 4 For $n = 3$,$2^3 = 8 \geqslant 5$.Thus,the minimum value of $n$ is $3$.

How many times must a fair coin be tossed so that the probability of getting at least one head is at least $0.8$?

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