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) 4/17

B) 4/45

C) 4/19

D) 1/2

Answer 1

Correct option is: B)\(\frac{4}{45}\)

Total No of discs = 90

Prime numbers less than 23 are 2, 3, 5, 7, 11, 13, 17, 19

Total No of prime numbers less than 23 are 8.

\(\therefore\) Probability that selected disc bears a prime number

less than 23 = \(\frac {Total \,No \,of \,prime \,numbers\, less \,than \,23}{Total \,No \,of \,discs}\) 

= \(\frac 8{90} = \frac 4{45}\) 

Answer 2

Correct option is: B) \(\frac{4}{45}\)