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Question
Prepare a continuous grouped frequency distribution from the following data:
| Mid-point | Frequency |
| 5 | 4 |
| 15 | 8 |
| 25 | 13 |
| 35 | 12 |
| 45 | 6 |
Also find the size of class intervals.
Solution
The common difference of mid-point = 15 – 5 = 10
Let lower limit is a. So, upper limit will be = a + 10
As we know that:
Mid-value = `("Lower limit" + "Upper limit")/2`
`5 = (a + a + 10)/2`
2a + 10 = 10
2a = 10 – 10
a = 0
Therefore, the first interval is 0 – 10.
Now, a frequency distribution table for the given data is given below:
| Mid-point | Class interval | Frequency |
| 5 | 0 – 10 | 4 |
| 15 | 10 – 20 | 8 |
| 25 | 20 – 30 | 13 |
| 35 | 30 – 40 | 12 |
| 45 | 40 – 50 | 6 |
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