Question

A man has $10$ shillings and one of them is known to have two heads. He takes one at random and tosses it $5$ times and it always falls head. What is the chance that it is the shilling with two heads?

Answer 1

Taking out two head shilling has probability$=\frac{1}{10}$
Getting head from this shilling has probability$=1$
So, Required probability$\Rightarrow \frac{1}{10}\times 1\times 1\times 1\times 1\times 1$
$\Rightarrow \frac{1}{10}$