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Question
Find the mean of the following distribution:
| Class interval | 0 - 10 | 10 - 20 | 20 - 30 | 30 - 40 | 40 - 50 |
| Frequency | 10 | 6 | 8 | 12 | 5 |
Solution
| Class Interval |
Frequency (f) |
Mid value x |
fx |
| 0 - 10 | 10 | 5 | 50 |
| 10 - 20 | 6 | 15 | 90 |
| 20 - 30 | 8 | 25 | 200 |
| 30 - 40 | 12 | 35 | 420 |
| 40 - 50 | 5 | 45 | 225 |
| `sumf` = 41 | `sumfx` = 985 |
∴ Mean = `(sumfx)/(sumf) = (985)/(41)`
= 24·02.
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