How can pick odds or even be fair?

Question

A even number plus a even number goes even and a odd number plus a odd number goes even too.

The only chance to get a odd number is a even and an odd.

How it cannot be 2/3 and 1/3 ?

In: Mathematics

Answer 1

Not sure if I understand what the question is.

Regardless, I hope the following will give some insight:

If you pick 2 numbers, X and Y, at random, X and Y can either be even, or odd. So, we have the following 4 possibilities. (Not 3)

– X, Y are both even -> sum is even

– X is even, Y is odd -> sum is odd

– X is odd, Y is even -> sum is odd

– X, Y are both odd -> sum is even

I think now it’s easy so see that the odds are 1/2 and 1/2.

Edit: formatting