PROBABILITY 1

Given the interval of 1-15 inclusive, Find the probability of having an even number or a prime number.

Solution

This is a non-mutually exclusive event.

n(S) = number of sample space = 15

Let P(E)= probability of even numbers = ⁷/15

Let P(R)= probability of prime  numbers = ⁶/15

P(EnR) = probability of having both even and prime numbers= ¹/15 [since even 2 is both even and prime]

∴ P(EuR) = P(E) + P(R)  - P(EnR).

 P(EuR) =  7  +  6 – 1

                15    15   15

P(EuR) =    13   -   1 

                  15      15  

P(EuR) =    12  or   4

                  15        5 

Hence probability of an even number or a prime number is ^4/5.

TRY THIS........

Given the interval of 1 - 23 inclusive, find the probability of having an even number or a prime number.