Question

A fair coin is tossed five times. Find the probability that it shows exactly three times head.

Answer 1

Total number of possible solutions ${}^5{C}_3$.
Total number of solutions $2^5=32$
Therefore $P\left(HHH\right)=\frac{{}^5{C}_3}{32}$
$=\frac{10}{32}=\frac{5}{16}$