Q39 of 66 Page 15

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.[CBSE 2011]

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

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