Find the average of the first 20 multiples of 9.

Solution (By Examveda Team)

First 20 multiple of 9

$$\eqalign{ & {\text{Average}} = \frac{{90 + 99}}{2} \cr & = 45 + 49.5 \cr & = 94.5{\text{ Answer}} \cr & \cr & {\bf{Alternate \,Solution:}} \cr & {\text{Average}} = \frac{{{\text{First term}} + {\text{Last term}}}}{2} \cr & = \frac{{9 + 180}}{2} \cr & = 4.5 + 90 \cr & = 94.5 \cr} $$