###
**The average age of an adult class is 40 years. 12 new students with an average age of 32 years join the class, thereby decreasing the average by 4 years. The original strength of the class was-**

A. 10
B. 11
C. 12
D. 15
**Answer: Option C**

## Show Answer

Solution(By Apex Team)

Let the original strength of the class be x
Sum of ages of the whole class = 40x years
Sum of ages of 12 now students
= (12 × 32) years
= 384 years
$\begin{aligned}\frac{40x+384}{x+12}=36\\
\end{aligned}$
$\begin{array}{l}
\Rightarrow 40 x+384=36 x+432 \\
\Rightarrow 4 x=48 \\
\Rightarrow x=12
\end{array}$
Hence, the original strength of the class = 12

## Related Questions On Average

### Ajit has a certain average for 9 innings. In the tenth innings, he scores 100 runs thereby increasing his average19 people went to a hotel for combine dinner party 13 by 8 runs. His new average is:

A. 20B. 21

C. 28

D. 32

### Find the average of all the numbers between 6 and 34 which are divisible by 5.

A. 18B. 20

C. 24

D. 30

### In a family, the average age of a father and a mother is 35 years. The average age of the father, mother and their only son is 27 years. What is the age of the son?

A. 10 yearsB. 10.5 years

C. 11 years

D. 12 years

### If the arithmetic mean of 0, 5, 4, 3 is a, that of -1, 0, 1, 5, 4, 3 is b and that of 5, 4, 3 is c, then the relation between a, b, and c is.

A. a = b = cB. a : b : c = 3 : 2 : 4

C. 4a = 5b = c

D. a + b + c = 12