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 odd?

Answer 1

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

Let E₃ = event of getting an odd number
Then E₃ = {1, 3, 5, 7, 9, 11, 13, 15, 17, 19}
i.e. n(E₃) = 10
Hence, required probability = P(E₃) = \[\frac{10}{20} = \frac{1}{2}\]