Question

20 cards numbered 1, 2, 3, 4, ….19, 20 are put in a box. One boy draws a card from the box. Find the probability that the number on the card is: 

i. Prime 

ii. Divisible by 3

Answer 1

Total number of outcomes = 20

a. Prime numbers from 1 to 17 are 2, 3, 5, 7, 11,13, 17, 19.

Number of outcomes = 8

The probability that the card drawn is prime number = 8/20

b. Numbers are divisible by 3 are 3, 6, 9, 12, 15, 18.

Number of outcomes = 6 

The probability that the card drawn is divisible by 3 = 6/20