Question

The following data give the number of boys of a particular age in a class of 40 students.
$\begin{array}{ccccccc}\text{Age (in years)}& 15& 16& 17& 18& 19& 20\\ \text{Frequency}\left(f_i\right)& 3& 8& 9& 11& 6& 3\end{array}$
Calculate the mean ager of the students.

Answer 1

Sol:

For calculating the mean, we prepare the following frequency table:

Age ( in years ) (xixi)	Frequency (fifi)	xififixi
15	3	45
16	8	128
17	9	153
18	11	198
19	6	114
20	3	60
	12Σfi=12	Σfixi=698

Mean = 698/12ΣfixiΣfi=69840=17.45 kg

Therefore, the mean age of the students = 17.45 kg