Question

A number is chosen at random among the first 100 natural numbers. Find the probability that the number chosen is prime.

• A. $\frac{1}{4}$
• B. $\frac{27}{100}$
• C. $\frac{3}{10}$
• D. $\frac{29}{100}$

Answer 1

The correct option is A

$\frac{1}{4}$

There are 25 prime numbers in the set of the first 100 natural numbers. They are:
2,3,5,7,11,13,17,19,23,29,31,37,41,43,47,53,59,61,67,71,73,79,83,89, and 97.
We know that, Probability of an event E, P(E) =$\frac{\text{number of favourable outcomes}}{\text{total number of outcomes}}$

Hence, the required probability = $\frac{25}{100}$ = $\frac{1}{4}$.