Question

Two unbiased coins are tossed simultaneously.find the probability of getting at most $1$ head?

Answer 1

When two coins are tossed simultaneously then the possible outcomes obtained are $\{HH,HT,TH,TT\}$.

Here $H$ denotes head and $T$ denotes tail.

$\therefore$, a total of $4$ outcomes obtained on tossing two coins simultaneously.

Consider the event of obtaining at the most one head. At most one head is obtained means either no head is obtained or one head is obtained.

The outcome favourable to no head obtained is $\left\{TT\right\}$

The outcome favourable to one head obtained is $\{HT,TH\}$

$\therefore$, the event of obtaining at most one head has $3$ favourable outcomes.

These are $TT,HT$ and $TH$.

$\therefore$, the probability of obtaining at most one head $=\frac{3}{4}$