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Question
Find the mean of the following frequency distribution :
| Class | 1-10 | 11-20 | 21-30 | 31-40 | 41-50 |
| Frequency | 9 | 12 | 15 | 10 | 14 |
Solution
| Class Interval | xi | fi | fixi |
| 1-10 | 5.5 | 9 | 49.5 |
| 11-20 | 15.5 | 12 | 186 |
| 21-30 | 25.5 | 15 | 382.5 |
| 31-40 | 35.5 | 10 | 355 |
| 41-50 | 45.5 | 14 | 637 |
| Total | 60 | 1610 |
`barx = (Σf_iX_i)/(Σ"f")`
`barx = 1610/60`
`barx = 26.83`
∴ Mean = 26.83
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