Question

Three unbiased coins are tossed simultaneously. The probability of getting at least two tails is

• A.
  $\frac{3}{8}$
• B.
  $\frac{1}{3}$
• C.
  $\frac{1}{8}$
• D.
  $\frac{1}{2}$

Answer 1

The correct option is D

$\frac{1}{2}$
When three coins are tossed simultaneously, the possible outcomes are $(H,H,H),(H,H,T),(H,T,H),(T,H,H),(H,T,T),(T,H,T),(T,T,H),(T,T,T),$ which are equally likely.

$\therefore$ Total number of outcomes = 8

Let E be an event of getting at least two tails.

The outcomes favourable to event E are $(H,T,T),(T,H,T),(T,T,H),(T,T,T).$

$\therefore$ Number of outcomes favourable to E = 4
$P\left(E\right)=\frac{Nooffavourableoutcomes}{Totalnoofoutcomes}$
$\Rightarrow \frac{4}{8}=\frac{1}{2}$
Hence, the correct answer is option (d).