Q10 of 54 Page 320

A box contains 90 discs which are numbered from 1 to 90. If one disc is selected at random from the box, find the probability that it bears.

a perfect square number

There are 90 discs in a box.

⇒ Number of outcomes in which discs is selected = 90.


⇒ Total perfect square in the box –


⇒ 12 = 1


⇒ 22 = 4


⇒ 32 = 9


⇒ 42 = 16


⇒ 52 = 25


⇒ 62 = 36


⇒ 72 = 49


⇒ 82 = 64


⇒ 92 = 81


⇒ Number of favourable cases = 9


⇒ Probability that discs bears a perfect square number –


⇒ P(Perfect square numbers) =


⇒ P(Perfect square numbers) =


⇒ P(Perfect square numbers) =


∴ Probability that discs bears a perfect square number is


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