Question

A box contains cards numbered from 1 to 20. A card is drawn at random from the box. Find the probability that number on the drawn card is (i) a prime number (ii) a composite number (iii) a number divisible by 3

Answer 1

a prime no. - 8/20
a no. divisible by 3- 6/20
a composite no.- 11/20

Answer 2

Answer :

A box contains number 1 to 20

So, Total number of outcomes = 20

Now, we need to find the probability :

1. A prime number

The prime numbers from 1 to 20 are : 2, 3, 5, 7, 11 , 13, 17, 19

No. of prime numbers = 8

So, Probability = 8/20

2. A composite number :

No. of composite numbers from 1 to 20 are : 11

So, Probability = 11/20

3. A number divisible by 3

numbers which are divisible by 3 : 3 , 6 , 9, 12, 15, 18

No. of numbers which are divisible by 3 from 1 to 20 = 6

So, Probability = 6/20