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 |
We will solve this using direct method.
LITERACY RATE(%) | MID - POINT(xi) | NUMBER OF CITIES(fi) | fixi |
45 - 55 | 50 | 4 | 200 |
55 - 65 | 60 | 11 | 660 |
65 - 75 | 70 | 12 | 840 |
75 - 85 | 80 | 9 | 720 |
85 - 95 | 90 | 4 | 360 |
TOTAL | 40 | 2780 |
We have got
Σfi = 40 and Σfixi = 2780
∵ mean is given by
⇒
⇒
Thus, mean is 69.5%.