Question

A box contains 80 discs, which are numbered from 1 to 80. If one disc is drawn at random from the box, find the probability that it bears a perfect square number.

Answer 1

Total number of outcomes = 80.

Let E₁ be the event of getting a perfect square number.

Out of these numbers, perfect square numbers are 1, 4, 9, 16, 25, 36, 49 and 64.

Thus, number of favourable outcomes = 8.

∴ P(getting a perfect square number) = P(E₁) = `("Number of outcomes favourable to"  E_1)/"Number of all possible outcomes"`

`= 8/80 = 1/10`

Thus, the probability that the disc bears a perfect square number is `1/10`.