PROBABILITY 2

Given the interval of 21 -32 inclusive, Find the probability of having an even number or a prime number.

Solution

This is a mutually exclusive event.

n(S) = number of sample space = 12

Even numbers(E): 22, 24, 26, 28, 30, 32 = 6

Prime numbers(P): 23, 39, 31 = 3

Let P(E)= probability of even numbers = ⁶/12

Let P(R)= probability of prime  numbers = ³/12

P(EnR) = probability of having both even and prime numbers= ⁰/12

∴ P(EuR) = P(E) + P(R)  - P(EnR).

 P(EuR) =  6  +  3 – 0

                12    12   12

P(EuR) =  9  -   0

                12     12  

P(EuR) =  9  =  3

               12     4      

Hence probability of an even number or a prime number is ^3/4.

TRY THIS.....................

Given the interval of 3 -18 inclusive, find the probability of having an even number or a prime number.