Question

If three unbiased coins are tossed at a time, then the probability of getting atmost one head is

• A. $\frac{1}{2}$
• B. $\frac{1}{4}$
• C. $\frac{1}{8}$
• D. $\frac{3}{8}$

Answer 1

The correct option is A $\frac{1}{2}$

Sample space of the given experiment is
$S=\{HHH,HHT,HTH,THH,HTT,THT,TTH,TTT\}$
Let $A$ be the event ''getting atmost head''
$A=\{HTT,THT,TTH,TTT\}$ i.e. $n\left(A\right)=4$
$\therefore P\left(A\right)=\frac{n\left(A\right)}{n\left(S\right)}=\frac{4}{8}=\frac{1}{2}$