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Question
Calculate the mean of the following distribution :
| Class Interval | 0-10 | 10-20 | 20-30 | 30-40 | 40-50 | 50-60 |
| Frequency | 8 | 5 | 12 | 35 | 24 | 16 |
Solution
Consider the following distribution:
| Class Interval | Frequency (f) | Classmark (x) | fx |
| 0 – 10 | 8 | 5 | 40 |
| 10 – 20 | 5 | 15 | 75 |
| 20 – 30 | 12 | 25 | 300 |
| 30 – 40 | 35 | 35 | 1225 |
| 40 – 50 | 24 | 45 | 1080 |
| 50 – 60 | 16 | 55 | 880 |
| Total | `n = sum f = 100` | `sum fx = 3600` |
Mean = `(sum fx)/n = 3600/100 = 36`
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