PROBABILITY 1

A number is chosen at random from 15 – 32 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, 25, 26, 27, 28, 29, 30, 31, 32} = 18

n(M) = {22, 24, 26, 28, 30, 32 } = 9

n(R) = {17, 19, 23, 29, 31} = 5

P(M) = ⁶/18

P(R) = ⁵/18

………………………….

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

P(MuR) = ⁶/18 + ⁵/18

              = ¹¹/18

              Hence      P(MuR) = ¹¹/18    answer

TRY THIS…………………

A number is chosen at random from 19 – 30 inclusive. Find the probability that it is a prime number or a multiple of 5.