The average of the first twelve multiples of 11 is:

Correct option is B

Given:

The first twelve multiples of 11 are:
11, 22, 33, 44, 55, 66, 77, 88, 99, 110, 121, and 132.

Formula Used:

The formula to calculate the average of a set of numbers is:
​$$\text{Average} = \frac{\text{Sum of all terms}}{\text{Number of terms}}$$​​

Solution:

The sum of the first twelve multiples of 11.
The sum is:
11 + 22 + 33 + 44 + 55 + 66 + 77 + 88 + 99 + 110 + 121 + 132 = 858

The average using the formula:
​$$\text{Average} = \frac{\text{Sum of all terms}}{\text{Number of terms}}$$​​

Substitute the values: Average  = $$\frac{858}{12} = 71.5$$​​

The average of the first twelve multiples of 11 is $$\boxed{71.5}$$​​