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Question
Find the mean using direct method:
| Class | 0-10 | 10-20 | 20-30 | 30-40 | 40-50 | 50-60 |
| Frequency | 7 | 5 | 6 | 12 | 8 | 2 |
Solution
| Class | Frequency`(f_i)` | Mid values `(x_i)` | `f_i xx x_i` |
| 0-10 | 7 | 5 | 35 |
| 10-20 | 5 | 15 | 75 |
| 20-30 | 6 | 25 | 150 |
| 30-40 | 12 | 35 | 420 |
| 40-50 | 8 | 45 | 360 |
| 50-60 | 2 | 55 | 110 |
| `∑ f_i = 40` | `∑(f_1xxx_1)=1150` |
∴ Mean , x = `(∑ (f_ixxx_i))/(∑ f_i)`
=` 1150/40`
=28.75
∴ x = 28.75
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