Question

The minimum number of times a fair coin needs to be tossed, so that the probability of getting at lest two heads is at least $0.96$, is

Answer 1

The probability of getting exactly $0$ heads in $n$ tosses is $=\frac{1}{2^n}$
The probability of getting exactly $1$ head in $n$ tosses is $\frac{{}^n{C}_1}{2^n}$
The probability of getting at least $2$ heads $=1-\frac{1+n}{2^n}$
The probability of getting at least $2$ heads is $0.96$.
Hence, $\frac{1+n}{2^n}<0.04$
The least value of $n$ which is $8$.