PROBABILITY 1

A number is chosen at random from 15 – 24 inclusive. Find the probability that it is a prime or a multiple of 2.

Solution

THIS IS A MUTUALLY EXCLUSIVE EVENT

Let n(S) represent sample space

P(M) = probability of a multiple of 2

P(R) = probability of prime number

n(S) = {15, 16, 17, 18, 19, 20, 21, 22, 23, 24} = 10

n(M) = {16, 18, 20, 22, 24, 26 } = 6

n(R) = {17, 19, 23} = 3

P(M) = ⁶/10

P(R) = ³/10

………………………….

P(MuR) = P(M) + P(R)

P(MuR) = ⁶/10 + ³/10

              = ⁹/10

P(MuR) = ⁹/10 answer

TRY THIS…………………

A number is chosen at random from 16 – 30 inclusive. Find the probability that it is a prime number or a multiple of 3.