PROBABILITY 1

Given the interval of 3 -12 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 = 10

Even numbers: 4,6,8,10,12 = 5

Prime numbers: 5,7,8,11 = 4

Let P(E)= probability of even numbers = ⁵/10

Let P(R)= probability of prime  numbers = ⁴/10

P(EnR) = probability of having both even and prime numbers= ⁰/10

∴ P(EuR) = P(E) + P(R)  - P(EnR).

 P(EuR) =  5  +  4 – 0

               10    10   10

P(EuR) =  9  -   0

              10     10  

P(EuR) =  9 

              10      

Hence probability of an even number or a prime number is ^9/10.

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

Given the interval of 3 -15 inclusive, find the probability of having an even number or a prime number.