Question

20 cards are numbered from 1 to 20. One card is drawn at random. What is the probability that the number on the cards is  divisible by 5?

Answer 1

Clearly, the sample space is given by S = {1, 2, 3, 4, 5........19, 20}.
i.e. n(S) = 20

Let E₅ = event of getting a number divisible by 5
Then E₅ = {5, 10, 15, 20}
i.e. n(E₅) = 4
Hence, required probability = P(E₅) = \[\frac{4}{20} = \frac{1}{5}\]