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प्रश्न
Find the mean of the distribution:
| Class | 1 – 3 | 3 – 5 | 5 – 7 | 7 – 10 |
| Frequency | 9 | 22 | 27 | 17 |
उत्तर
We first, find the class mark xi of each class and then proceed as follows.
| Class | Class marks `(bb(x_i))` |
Frequency `(bb(f_i))` |
`bb(f_ix_i)` |
| 1 – 3 | 2 | 9 | 18 |
| 3 – 5 | 4 | 22 | 88 |
| 5 – 7 | 6 | 27 | 162 |
| 7 – 10 | 8.5 | 17 | 144.5 |
| `sumf_i = 75` | `sumf_ix_i = 412.5` |
Therefore, mean `(barx) = (sumf_ix_i)/(sumf_i)`
= `412.5/75`
= 5.5
Hence, mean of the given distribution is 5.5.
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