What is the average of the odd numbers from 1 to 35?

The correct answer is Option (3) → 18

The odd numbers go up by the same step of 2, so their average is the average of the first and the last number.

• The odd numbers are 1, 3, 5, …, 35

• \(\displaystyle \text{Average}=\frac{1+35}{2}=18\)

The average is 18. (There are 18 such numbers with sum \(18^{2}=324\), and \(324\div18=18\).)