A. 20

B. 27

C. 28

D. 30

### Solution(By Apex Team)

$\begin{array}{l}\text{Required average}\\ \begin{array}{l} =\Large\frac{\text { total sum of multiple of } 9}{5} \\ =\Large\frac{9+18+27+36+45}{5} \\ =27 \end{array}\end{array}$
Note that, average of 9 and 45 is also 27. And average of 18 and 36 is also 27.

A. 20
B. 21
C. 28
D. 32

A. 18
B. 20
C. 24
D. 30

A. 10 years
B. 10.5 years
C. 11 years
D. 12 years