The average age of 40 students in a class is 12 years. The average age of group of 5 of students is 10 years and that of another group of 5 of them is 14 years. The average age of the remaining students is:

Correct option is B

Given:

Total students = 40

Average age of all = 12 years

Average age of 1st group (5 students) = 10 years

Average age of 2nd group (5 students) = 14 years

Find average age of remaining 30 students.

Formula Used:

total sum = average × number of students

Solution:

Total sum of all students = 40 × 12 = 480 years

Sum of 1st group = 5 ×10 = 50 years

Sum of 2nd group = 5 × 14 = 70 years

Remaining students = 40 - 10 = 30

Remaining total = 480 - 50 - 70 = 360 years

Average age of remaining 30 = $$\frac{360}{30}$$​ = 12 years