Question

If 15 is the fifth number in a series of 5 consecutive odd number, what is the third number in the series?

Answer 1

You really don't have to do hardly ANY work to solve this one.

The fifth of five odd numbers is 15.

So the fourth one is 13.

So the third one is 11.

An I missing something ?

Answer 2

The five numbers can be represented by (2n+1), (2n+3), (2n+5), (2n+7) and (2n+9) where
n is an integer.
2n+9 = 15
n = 3

The third number is 2n+5 = 11