What is the average of the first five odd multiples of 3?

The correct answer is Option (3) → 15

The odd multiples of 3 are 3 times the odd numbers, and they go up by the same step of 6, so their average is the middle term.

• The first five odd multiples of 3 are \(3\times1, 3\times3, 3\times5, 3\times7, 3\times9\), that is, 3, 9, 15, 21, 27

• Sum \(=3+9+15+21+27=75\)

• \(\displaystyle \text{Average}=\frac{75}{5}=15\)

The average is 15, the middle term of the five.