Question

Three unbiased coins are tossed. The probability of getting at least $2$ tails is

• A. $\frac{3}{4}$
• B. $\frac{1}{4}$
• C. $\frac{1}{2}$
• D. $\frac{1}{3}$
• E. $\frac{2}{3}$

Answer 1

Answer: (C)

Total numbers of outcomes when three coins are tossed
$=2 \times 2 \times 2=8$
$\therefore n(S)=8$
Let $E=$ Event getting at least 2 tails
$=\{T T H, T H T, T T H, T T T\}$
$\therefore n(E)=4$
$\therefore $ Required probability $=P(E)$
$=\frac{n(E)}{n(S)}$
$=\frac{4}{8}$
$=\frac{1}{2}$