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Question
Find the mean of the following frequency distribution :
| Class | 0-10 | 10-20 | 20-30 | 30-40 | 40-50 |
| Frequency | 4 | 7 | 6 | 3 | 5 |
Solution
| Class Interval | Xi | fi | fiXi |
| 0-10 | 5 | 4 | 20 |
| 10-20 | 15 | 7 | 105 |
| 20-30 | 25 | 6 | 150 |
| 30-40 | 35 | 3 | 105 |
| 40-50 | 45 | 5 | 225 |
| Total | 25 | 605 |
`barx = (Σf_iX_i)/(Σ"f")`
`barx = 605/25`
`barx = 24.2`
∴ Mean = 24.2
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