The average of the first 5 multiples of 9 is .

The correct option is A 27
$\text{Average}=\frac{\text{Sum of the observations}}{\text{Total number of observations}}$

The first 5 multiples of 9 are 9, 18, 27, 36 and 45.

$⟹\text{Average}=\frac{9+18+27+36+45}{5}$
$=\frac{135}{5}$
$=27$