Question :
| Literacy rate (in %) | 45 – 55 | 55 – 65 | 65 – 75 | 75 – 85 | 85 – 95 |
| Number of cities | 3 | 10 | 11 | 8 | 3 |
Solution :
Let the assumed mean, A = 70 and class size, h = 10
So, \(u_i\) = \(x_i – 70\over 10\)
| Literacy rate (in %) | Mid-value (\(x_i\)) | Frequency (\(f_i\)) | \(u_i\) = \(x_i – 70\over 10\) | \(f_iu_i\) |
| 45 – 55 | 50 | 3 | -2 | -6 |
| 55 – 65 | 60 | 10 | -1 | -10 |
| 65 – 75 | 70 | 11 | 0 | 0 |
| 75 – 85 | 80 | 8 | 1 | 8 |
| 85 – 95 | 90 | 3 | 2 | 6 |
| Total | 35 | -2 |
Mean = A + h \(\times\) \(\sum f_iu_i\over \sum f_i\)
= 70 + 10 \(\times\) \(-2\over 35\) = 70 – 0.57 = 69.43%
Thus, mean literacy rate is 69.43%
