# If a number is chosen at random from the following list, what is the probability that it is not prime? 2, 3, 5, 7, 11, 13, 17, 19

### 2 Answers | Add Yours

We have the numbers:

2, 3, 5, 7, 11, 13, 17, 19

The prime number is an integer that is dividible by 1 and itself only.

We notice that all the abpve numbers are prime numbers.

Then the probability of getting a prime = 8/8 = 1

This is called a certain event.

The probability of getting a number that si NOT a prime = 0/8= 0

This is called an impossible event.

The list numbers given is: 2,3,5,7,11,13, 17 and 19.

The number of numbers are 8.

Each of these numbers are prime.

So the number of choices to make in a random choice = 8.

Since all the 8 numbers given in this list , 2,3,5,7,11,13 , 17 and 19, are primes, we are sure that any number chosen is a prime number.

Therefore number of favourable choices = 8.

The number possible choices is 8.

Therefore the probability that a chosen number from the list at random (or otherwise) is a prime = 8/8 = 1.