Question

Calculate the mean of the following data : Class $4-7,8-11,12-15,16-19$ Frequency $5,4,9,10$

Answer 1

Calculate the mean of given data:

The given data is not continuous.

So, we subtract 0.5 from the lower limit and add 0.5 in the upper limit of each class.

Class	Class Marks (xi)	Frequency (fi)	fixi
3.5 – 7.5	5.5	5	27.5
7.5 – 11.5	9.5	4	38
11.5 – 15.5	13.5	9	121.5
15.5 – 19.5	17.5	10	175
Σfi = 28	Σfixi = 362

Mean $\begin{array}{rcl}\overline{x}& =& \frac{{\displaystyle \sum _{}}{f}_i{x}_i}{{\displaystyle \sum _{}}{f}_i}\end{array}$

$\begin{array}{rcl}& =& \frac{362}{28}\\ & =& 12.93\end{array}$

Therefore, mean of the given data $12.93$