Question

Using an appropriate method, find the mean of following frequency distribution:

Class interval	84−90	90−96	96−102	102−108	108−114	114−120
Frequency	8	10	16	23	12	11

Which method did you use, and why?

Answer 1

The given data is shown as follows:

Class interval	Frequency (fi)	Class mark (xi)	fixi
84−90	8	87	696
90−96	10	93	930
96−102	16	99	1584
102−108	23	105	2415
108−114	12	111	1332
114−120	11	117	1287
Total	∑ fi = 80		∑ fixi = 8244

The mean of given data is given by

$$\begin{gathered} \overline{x}=\frac{{\displaystyle \sum _i}{f}_i{x}_i}{{\displaystyle \sum _i}{f}_i} \\ =\frac{8244}{80} \\ =103.05 \end{gathered}$$

​Thus, the mean of the following data is 103.05 .