The average of the first 18 positive multiples of 8 is:

The correct option is 76.

Let us find the average of the first 18 positive multiples of 8 step-by-step.

The first 18 positive multiples of 8 are:
8, 16, 24, 32, ..., (18 × 8)

This sequence of numbers forms an Arithmetic Progression (AP) where:
The first term (represented as a) is 8.
The common difference (represented as d) is 8.
The total number of terms (represented as n) is 18.
The last term (represented as l) is:
$$l=18\times 8=144$$

For any arithmetic progression, the average (arithmetic mean) of the terms is given by the formula:
$$\text{Average}=\frac{a+l}{2}$$
where a is the first term and l is the last term.

Substituting the values of a and l into the formula:
$$\text{Average}=\frac{8+144}{2}$$
$$\text{Average}=\frac{152}{2}$$
$$\text{Average}=76$$

Therefore, the average of the first 18 positive multiples of 8 is 76.