Question

Compute the mean of following data: [CBSE 2013]

Class	1−3	3−5	5−7	7−9
Frequency	12	22	27	19

Answer 1

The given data is shown as follows:

Class	Frequency (fi)	Class mark (xi)	fixi
1−3	12	2	24
3−5	22	4	88
5−7	27	6	162
7−9	19	8	152
Total	∑ fi = 80		∑ fixi = 426

The mean of given data is given by

$$\begin{gathered} \overline{x}=\frac{{\displaystyle \sum _i}{f}_i{x}_i}{{\displaystyle \sum _i}{f}_i} \\ =\frac{426}{80} \\ =5.325 \end{gathered}$$

Thus, the mean of the following data is 5.325.