Question

What is the average of first 16 multiples of 9?

• A. 72
• B. 76.5
• C. 77.25
• D. 79.75

Hint:

To find the average of an arithmetic sequence, use \( \frac{\text{First term} + \text{Last term}}{2} \), especially when the number of terms is even.

Answer 1

The Correct Option is B

The first 16 multiples of 9 are: \[ 9, 18, 27, \ldots, 9 \times 16 = 144 \] This forms an arithmetic progression (A.P.) where: - First term \( a = 9 \) - Number of terms \( n = 16 \) - Last term \( l = 144 \) The average of an A.P. is given by: \[ \text{Average} = \frac{\text{First term} + \text{Last term}}{2} = \frac{9 + 144}{2} = \frac{153}{2} = 76.5 \]