Question

Calculate the average age of students in a class using Assumed mean method.

• A. $9$ years
• B. $7$ years
• C. $12$ years
• D. $13$ years

Answer 1

The correct option is B $7$ years

Age (x)	Students (f)	d=x-A	fd
5	20	-2	-40
6	25	-1	-25
7= A	30	0	0
8	35	1	35
9	40	2	80
	$\Sigma f=150$		$\Sigma fd=50$

Mean (By Shortcut method) = $A+\frac{\Sigma fd}{\Sigma f}=7+\frac{50}{150}=7+0.33=7.33$

Average age = 7 years