Question

The following table gives the literacy rate (in percentage) in 40 cities. Find the mean literacy rate, choosing a suitable method.

Literacy rate (%)	45−55	55−65	65−75	75−85	85−95
Number of cities	4	11	12	9	4

Answer 1

Using Direct method, the given data is shown as follows:

Literacy rate (%)	Number of cities (fi)	Class mark (xi)	fixi
45−55	4	50	200
55−65	11	60	660
65−75	12	70	840
75−85	9	80	720
85−95	4	90	360
Total	∑ fi = 40		∑ fixi = 2780

The mean of given data is given by

$$\begin{gathered} \overline{x}=\frac{{\displaystyle \sum _i}{f}_i{x}_i}{{\displaystyle \sum _i}{f}_i} \\ =\frac{2780}{40} \\ =69.5 \end{gathered}$$

​Thus, the mean literacy rate is 69.5%.