Question

The probability of getting at least one head when we toss $3$ unbiased coin is

• A. $\frac{3}{8}$
• B. $\frac{5}{8}$
• C. $\frac{7}{8}$
• D. $\frac{1}{8}$

Answer 1

Answer: (C)

$\frac{7}{8}$

Probability of getting at least one head $=$ $1$ $-$ Probability of getting zero heads
Probability of getting zero heads $=$ Probability of getting all tails $\left(TTT\right)$ $=\frac{1}{2^3}$
Probability of getting at least one head $1-\frac{1}{8}=\frac{7}{8}$