Find the average of the first 10 multiples of 7:

The correct answer is Option (4) → 38.5

The first 10 multiples of 7 (7, 14, …, 70) go up in equal steps, and the average of numbers in equal steps is the average of the first and the last.

• First multiple: 7; tenth multiple: \(7\times10=70\)

• Average \(\displaystyle=\frac{7+70}{2}=38.5\)