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प्रश्न
The mean of the following distribution is 52 and the frequency of class interval 30-40 is ‘f’. Find ‘f’.
| Class Interval | 10-20 | 20-30 | 30-40 | 40-50 | 50-60 | 60-70 | 70-80 |
| Frequency | 5 | 3 | f | 7 | 2 | 6 | 13 |
उत्तर
The mean of the distribution is frequency
| C.I. | Frequency (f) |
Mid Value (x) |
fx |
| 10-20 | 5 | 15 | 75 |
| 20-30 | 3 | 25 | 75 |
| 30-40 | f | 35 | 35f |
| 40-50 | 7 | 45 | 315 |
| 50-60 | 2 | 55 | 110 |
| 60-70 | 6 | 65 | 390 |
| 70-80 | 13 | 75 | 975 |
| `sumf = 36 + f` | `sum fx = 1940 + 35 f` |
Mean = `(sumfx)/(sumf)`
`=> 52 = (1940 + 35f)/(36 + f)`
`=>` 1872 + 52f = 1940 + 35f
`=>` 17f = 68
∴ f = 4
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संबंधित प्रश्न
From the following cumulative frequency table, draw ogive and then use it to find:
- Median
- Lower quartile
- Upper quartile
| Marks (less than) | 10 | 20 | 30 | 40 | 50 | 60 | 70 | 80 | 90 | 100 |
| Cumulative frequency | 5 | 24 | 37 | 40 | 42 | 48 | 70 | 77 | 79 | 80 |
The daily wages of 80 workers in a building project are given below :
| Wages (Rs) | No.of workers |
| 30-40 | 6 |
| 40-50 | 10 |
| 50-60 | 15 |
| 60-70 | 19 |
| 70-80 | 12 |
| 80-90 | 8 |
| 90-100 | 6 |
| 100-110 | 4 |
Using graph paper, draw an ogive for the above distribution. Use your ogive, to estimate :
(1) the mediam wages of workers
(2) the percentage of workers who earn more than Rs 75 a day.
(3) the upper quartile wages of the workers
(4) the lower quartile wages of the workers
(5) Inter quartile range
Calculate the mean of the distribution, given below using the short cut method:
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| No. of students | 2 | 6 | 10 | 12 | 9 | 7 | 4 |
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| Class | 1-10 | 11-20 | 21-30 | 31-40 | 41-50 |
| Frequency | 9 | 12 | 15 | 10 | 14 |
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