# A box contains 90 discs which are numbered from 1 to 90. If one disc is drawn at random from the box, find the probability that it bears (i) a two-digit number (ii) a perfect square number (iii) a number divisible by 5

**Solution:**

We use the basic concepts of probability to solve the question.

Total number of discs = 90

Total number of 2 digit numbers between 1 to 90 = 81

Total number of perfect square numbers between1 to 90 are 1, 4, 9, 16, 25, 36, 49, 64, 81 = 9

Total numbers that are divisible by 5 are 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90 = 18

(i) Probability of getting a two digit number = Number of possible outcomes/Total no of favourable outcomes

= 81/90

= 9/10

(ii) Probability of getting a perfect square number = Number of possible outcomes/Total no of favourable outcomes

= 9/90

= 1/10

(iii) Probability of getting a number divisible by 5 = Number of possible outcomes/No of favourable outcomes

= 18/90

= 1/5

Check out more in terms of probability.

**Video Solution:**

## A box contains 90 discs which are numbered from 1 to 90. If one disc is drawn at random from the box, find the probability that it bears (i) a two-digit number (ii) a perfect square number (iii) a number divisible by 5

### NCERT Solutions for Class 10 Maths Chapter 15 Exercise 15.1 Question 18 - Chapter 15 Exercise 15.1 Question 18:

A box contains 90 discs which are numbered from 1 to 90. If one disc is drawn at random from the box, find the probability that it bears (i) a two-digit number (ii) a perfect square number (iii) a number divisible by 5

The probability that it bears (i) a two-digit number, (ii) a perfect square number, and (iii) a number divisible by 5 are 9/10, 1/10, and 1/5 respectively