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प्रश्न
Find the mean of the following frequency distribution :
| Class | 0-10 | 10-20 | 20-30 | 30-40 | 40-50 |
| Frequency | 4 | 7 | 6 | 3 | 5 |
उत्तर
| Class Interval | Xi | fi | fiXi |
| 0-10 | 5 | 4 | 20 |
| 10-20 | 15 | 7 | 105 |
| 20-30 | 25 | 6 | 150 |
| 30-40 | 35 | 3 | 105 |
| 40-50 | 45 | 5 | 225 |
| Total | 25 | 605 |
`barx = (Σf_iX_i)/(Σ"f")`
`barx = 605/25`
`barx = 24.2`
∴ Mean = 24.2
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संबंधित प्रश्न
The median is always one of the numbers in a data.
Calculate the mean of the following distribution using step deviation method.
| Marks | 0-10 | 10-20 | 20-30 | 30-40 | 40-50 | 50-60 |
| Number of students |
10 | 9 | 25 | 0 | 16 | 10 |
Marks obtained (in mathematics) by 9 students are given below:
60, 67, 52, 76, 50, 51, 74, 45 and 56
- Find the arithmetic mean.
- If marks of each student be increased by 4; what will be the new value of arithmetic mean?
The following table gives the weekly wages of workers in a factory.
| Weekly wages (Rs) | No. of workers |
| 50 – 55 | 5 |
| 55 – 60 | 20 |
| 60 – 65 | 10 |
| 65 – 70 | 10 |
| 70 – 75 | 9 |
| 75 – 80 | 6 |
| 80 – 85 | 12 |
| 85 – 90 | 8 |
Calculate the mean by using:
Direct Method
Find the mode of the following data:
7, 9, 8, 7, 7, 6, 8, 10, 7 and 6
The marks obtained by 120 students in a mathematics test is given below:
| Marks | No. of students |
| 0 – 10 | 5 |
| 10 – 20 | 9 |
| 20 – 30 | 16 |
| 30 – 40 | 22 |
| 40 – 50 | 26 |
| 50 – 60 | 18 |
| 60 – 70 | 11 |
| 70 – 80 | 6 |
| 80 – 90 | 4 |
| 90 – 100 | 3 |
Draw an ogive for the given distributions on a graph sheet. Use a suitable scale for your ogive. Use your ogive to estimate:
- the median
- the number of student who obtained more than 75% in test.
- the number of students who did not pass in the test if the pass percentage was 40.
- the lower quartile.
Out of 10 students, who appeared in a test, three secured less than 30 marks and 3 secured more than 75 marks. The marks secured by the remaining 4 students are 35, 48, 66 and 40. Find the median score of the whole group.
Find the mean of 53, 61, 60, 67 and 64.
Find the mean of first ten odd natural numbers.
Median of the data may or may not be from the given data.
