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

1.	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.
Answer» 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

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.

Answer»

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

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