Question

The average age of a group of 10 students was 20. The average age increased by 2 years when two new students joined the group. What is the average age of the two new students who joined the group? A. 22 years B. 30 years C. 44 years D. 32 years E. NOTA

Answer 1

Average age of a group of 10 students= 20.
The sum of the ages = 10 x 20 = 200

Now two new students join the group, the average age increases by 2. 

New average = 22.
No of students=12 
Sum of the ages of all 12 = 12 x 22 = 264

Difference of ages= 264 - 200 = 64

The average age of each of the two new students = 64/2 = 32 years.

Answer 2

Solution:-
The average age of a group of 10 students = 20 years
Sum of the ages of these 10 students = 10 × 20 = 200 years.
when 2 new students joined the average age is increased by = 2 years
Hence the average age becomes 22 years and total students become 12.
Therefore, the sum of the ages of the 12 students = 12 × 22 = 264 years
So, the difference between the sum of the ages of 12 students and 10 students = 264 - 200 = 64 years.
Sum of the ages of the 2 new students = 64 years.
Average age of the 2 new students = 64/2 
= 32 years.
So, the option 'D' is correct.