Question

Three unbiased coins are tossed. What is the probability of getting at at least two heads?

• A. $\frac{1}{2}$
• B. $\frac{1}{4}$
• C. $\frac{1}{5}$
• D. None of these

Answer 1

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

Atleast two heads means we can get two heads or three heads.

The probability of getting $2$ heads is $3\times \frac{1}{2}\times \frac{1}{2}\times \frac{1}{2}=\frac{3}{8}$.

The probability of getting $3$ heads is $1\times \frac{1}{2}\times \frac{1}{2}\times \frac{1}{2}$.

The probability of getting atleast two heads is $\frac{3}{8}+\frac{1}{8}=\frac{4}{8}=\frac{1}{2}$.

Therefore the correct option is $A$.