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

Since the eighty discs are numbered from 1 to 80, the total number of possible outcomes is 80. 

1, 4, 9, 16, 25, 36, 49 and 64 are the only perfect squares less than 80. 

Number of perfect squares from 1 to 80 = 8 

∴ Total number of favourable outcomes = 8 

Thus ,required probability =`\text{Total number of favourable outcomes}/\text{Total number of possible outcomes}=8/80=1/10`