Question

The following data give the number of boys of a particular age in a class of $40$ students. Calculate the mean age of the students.

Age(in years)	$13$	$14$	$15$	$16$	$17$	$18$
Number of students	$3$	$8$	$9$	$11$	$6$	$3$

Answer 1

Age (in years) x	Number of students$\left(f\right)$	$fx$
13	3	39
14	8	112
15	9	135
16	11	176
17	6	102
18	3	54
Total	40	618

Then, average mean $=\frac{\sum fx}{\sum f}=\frac{618}{40}=15.45$