Question

A box contains 90 discs which are numbered from 1 to 90. If one discs 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.

Answer 1

GIVEN: A box contains 90 discs which are numbered from 1 to 90.If one disc is drawn at random from the box

TO FIND: Probability that it bears

(i) a two digit number

(ii) a perfect square

(iii) a number divisible by 5

Total number of discs numbered is 90

(i) disc marked a two digit numbers are

Total number of disc marked two digit numbers from 1 to 90 are 81

We know that PROBABILITY =

Hence probability of getting disc marked with two digit numbers from 1 to 90 is

(ii) disc marked a perfect squared numbers are 1,4,9,16,25,36,49,64,81

Total number of disc marked perfect square numbers from 1 to 90 are 9

We know that PROBABILITY =

Hence probability of getting disc marked with perfect square numbers from 1 to 90 is

(iii) disc marked with a number divisible by 5 are 5,10,15,20,25,30,35,40,45,50,55,60,65,70,75,80,85,90

Total number of disc marked perfect square numbers from 1 to 90 are 18

We know that PROBABILITY =

Hence probability of getting disc marked number divisible by 5 from 1 to 90