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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 |
Solution
Using Direct method, the given data is shown as follows:
| Literacy rate (%) |
Number of cities `(f_i)` |
Class mark `(x_i)` | `(f_i x_i)` |
| 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 | `Ʃ f_i` = 40 | `Ʃ f_i x_i` = 2780 |
The mean of the data is given by,
x = `(Ʃ_i f_i x_i)/(Ʃ _i f_i)s`
=`2780/40`
= 69.5
Thus, the mean literacy rate is 69.5%.
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