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.
Total numbers of elementary events are: 80
The favourable numbers are: 1, 4, 9, 16, 25, 36, 49, 64
Then, the numbers of favourable outcomes = 8
∴ P (perfect square number) = P (E) = 8/80 = 1/10