NCERT Solutions for Class 10 Maths Chapter 15

Important NCERT Questions

PROBABILITY

NCERT Books for Session 2022-2023

CBSE Board and UP Board Others state Board

EXERCISE 9.1

Page No:309

Questions No: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.

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Total number of discs = 90

(i) Total number of two-digit numbers between 1 and 90 81

P (getting a two-digit number) = 81/90 = 9/10

(ii) Perfect squares between 1 and 90 are 1,4,9, 16, 25, 36, 49, 64, and 81.

Therefore, total number of perfect squares between 1 and 90 is 9.

P (getting a perfect square) = 9/90 = 1/10

(iii) Numbers that are between 1 and 90 and divisible by 5 are 5, 10, 15, 20, 25, 30, 35, 40, 45, 50 55, 60, 65, 70, 75, 80, 85, and 90.

Therefore, total numbers divisible by 5 = 18

Probability of getting a number divisible by 5 = 18/90 = 1/5