A fair die is rolled, find the probability of getting a prime number.

Number on a die = 1, 2, 3, 4, 5, 6

n(S) = 6

Prime numbers = 2, 3, 5

n(E) = 3

Probability = n(E) / n(S) = 3 / 6 = 1 / 2

Thus, the required probability = 1 / 2.