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प्रश्न
Find the mean of the following frequency distribution by the step deviation method :
| Class | 0-20 | 20-40 | 40-60 | 60-80 | 80-100 | 100-120 | 120-140 |
| Frequency | 12 | 24 | 52 | 88 | 66 | 42 | 16 |
उत्तर
| Class Interval | xi | fi | A = 70 `"u" = ("x - A")/"h"_i` |
`f_iu` |
| 0-20 | 10 | 12 | -3 | -36 |
| 20-40 | 30 | 24 | -2 | -48 |
| 40-60 | 50 | 52 | -1 | -52 |
| 60-80 | A = 70 | 88 | 0 | 0 |
| 80-100 | 90 | 66 | 1 | 66 |
| 100-120 | 110 | 42 | 2 | 84 |
| 120-140 | 130 | 16 | 3 | 48 |
| Total | 300 | 62 |
A= 70 and hi = 20
`barx = "A" + "h" xx (Σf_i "u")/(Σf_i)`
`barx = 70 + 20 xx 62/300`
`barx = 70 + 4.13`
`barx = 74.13`
∴ Mean = 74.13
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संबंधित प्रश्न
The following are the marks obtained by 70 boys in a class test:
| Marks | No. of boys |
| 30 – 40 | 10 |
| 40 – 50 | 12 |
| 50 – 60 | 14 |
| 60 – 70 | 12 |
| 70 – 80 | 9 |
| 80 – 90 | 7 |
| 90 – 100 | 6 |
Calculate the mean by:
Short-cut method
In a basket there are 10 tomatoes. The weight of each of these tomatoes in grams is as follows:
60, 70, 90, 95, 50, 65, 70, 80, 85, 95.
Find the median of the weights of tomatoes.
Find the median of the following:
11, 8, 15, 5, 9, 4, 19, 6, 18
The following observations have been arranged in ascending order. If the median of the data is 78, find the value of x.
44, 47, 63, 65, x + 13, 87, 93, 99, 110.
The mean of a certain number of observations is 32. Find the resulting mean, if the observation is, increased by 3
Mean of 5 numbers is 20 and the mean of the other 5 numbers is 30. Find the mean of all the 10 numbers taken together.
Find the mean and the median of: 10,12, 12, 15, 15, 17, 18, 18, 18 and 19
Find the median of the given data: 36, 44, 86, 31, 37, 44, 86, 35, 60, 51
Find the median of 25, 16, 15, 10, 8, 30
An incomplete frequency distribution is given below
| Variate | Frequency |
| 10 – 20 | 12 |
| 20 – 30 | 30 |
| 30 – 40 | ? |
| 40 – 50 | 65 |
| 50 – 60 | 45 |
| 60 – 70 | 25 |
| 70 – 80 | 18 |
| Total | 229 |
Median value is 46, the missing frequency is:
