Question

A box contains 90 discs, numbered from 1 to 90. If one disc is drawn at random from the box, the probability that it bears a prime-number less than 23, is :

• A. $\frac{7}{90}$
• B. $\frac{10}{90}$
• C. $\frac{4}{45}$
• D. $\frac{9}{89}$

Answer 1

The correct option is C $\frac{4}{45}$

Prime number less than 23 are 2,3,5,7,11,13,17,19
So favourable outcome $=\frac{8}{90}$
$=\frac{4}{45}$