Question

A bag contains 12 balls which are numbered from 1 to 12. If two ball are selected at random, what is the probability that the total sum of the balls will be an even number

Answer 1

5/11.

Explanation:

The number of ways 2 balls can be selected = 12P2

= 12!/10!

= 12*11

= 132.

There are 6 even numbers and 6 odd numbers in the bag.

If both numbers drawn are even there are 6P2 = 30 ways that sum is even.

If the 2 numbers are odd there are also 30 ways that sum is even.

Any other combination wil be odd.

So the required probabilit = 2(3) / 132

= 60/132

= 5/11.