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प्रश्न
Find the mean of the following frequency distribution:
| Class | 1 – 5 | 5 – 9 | 9 – 13 | 13 – 17 |
| Frequency | 4 | 8 | 7 | 6 |
उत्तर
| Class | Frequency | Midpoint `(bb(x_i))` |
`bb(f_ix_i)` |
| 1 – 5 | 4 | 3 | 12 |
| 5 – 9 | 8 | 7 | 56 |
| 9 – 13 | 7 | 11 | 77 |
| 13 – 17 | 6 | 15 | 90 |
| `sumf_i` = 25 | `sumf_ix_i` = 235 |
∴ Mean = `(sumf_ix_i)/(sumf_i)`
= `235/25`
= 9.4
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