Question

There are 25 discs numbered 1 to 25. They are put in a closed box and shaken thoroughly. A disc is drawn at random from the box. Find the probability that the number on the disc is : 

(i) an odd number 

(ii) divisible by 2 and 3 both 

(iii) a number less than 16.

Answer 1

Sample space = 25 discs numbered from 1 to 25. 

(i) Odd numbers are 1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, 25 

Probability (an odd number) = 13/25. 

(ii) Numbers divisible by 2 and 3 both are 6, 12, 18, 24

Probability (divisible by 2 and 3 both) = 4/25. 

Numbers less than 16 are 1 to 15 

(iii) Probability (a no. less than 16) = 15/25 or 3/5