Question

A number is selected from first 30 natural numbers.What is the probability that
if would be divisible by 2 or it is a prime​​

Answer 1

The probability that the number is a multiple of 3 is 10/30 since there 10 different numbers in first 30 which are multiple of 3 The probability that the number is a multiple of 13 is 2/30 since there 2 different numbers in first 30 which are multiple of 3 Neither 3 nor 13 has common multiple from 1 to 30. Hence these events are mutually exclusive events. Therefore chance that the selected number is a multiple of 3 or 13 is (10+2)/30 = 2/5