The minimum number of times a fair coin needs to be tossed, so that the probability of getting at least two…
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
$5$
$6$
$7$
$8$
Solution
The probability of getting exactly 1 head in $n$ toss $=\frac{1}{2^n}$ the probability of getting exactly 1 head in $\mathrm{n}$ toss $=\frac{{ }^n C_1}{2^n}$ The probability of getting at least 2 head $=1-\frac{n+1}{2^n}$
Now, $1-\frac{n+1}{2^n}>0.94 \Rightarrow 0.04>\frac{1+n}{2^n}$
So $\mathrm{n}=8$