PROBABILITY C2

A number is chosen at random from 5 – 10 inclusive. Find the probability that it is a prime or an even number.

Solution

Let n(S) represent sample space

P(E) = probability of even number

P(R) = probability of prime number

n(S) = {5, 6, 7, 8, 9, 10} = 6

n(E) = {6, 8, 10} = 3

n(R) = {5,7} = 2

P(E) = ³/6

P(R) = ²/6

………………………….

P(EuR) = P(E) + P(R)

P(EuR) = ³/6 + ²/6

P(EuR) = ⁵/6 answer

TRY THIS…………………

A number is chosen at random from 3 – 14 inclusive. Find the probability that it is a prime or an even number.