Question

A box contains $20$ cards marked with the numbers $1$ to $20$. One card is drawn from this box at random. What is the probability that number on the card, is a prime number?

• A. $\frac{1}{5}$
• B. $\frac{2}{5}$
• C. $\frac{1}{3}$
• D. $\frac{1}{2}$

Answer 1

Answer: (B)

$\frac{2}{5}$

$n\left(S\right)=20$....(Total number of events)

$n\left(E\right)=2,3,5,7,11,13,17,19=8$

Probablity= $\frac{n\left(E\right)}{n\left(S\right)}=\frac{8}{20}=\frac{2}{5}$

Hence, option $B$ is the correct answer.