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प्रश्न
Find the mean of the following frequency distribution :
| Class | 50-60 | 60-70 | 70-80 | 80-90 | 90-100 |
| Frequency | 8 | 6 | 12 | 11 | 13 |
उत्तर
| Class Interval | Xi | fi | fiXi |
| 50-60 | 55 | 8 | 440 |
| 60-70 | 65 | 6 | 390 |
| 70-80 | 75 | 12 | 900 |
| 80-90 | 85 | 11 | 935 |
| 90-100 | 95 | 13 | 1235 |
| Total | 50 | 3900 |
`barx = (Σf_iX_i)/(Σ"f")`
`barx = 3900/50`
`barx = 78`
`therefore` Mean = 78
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संबंधित प्रश्न
Calculate the mean of the following distribution :
| Class Interval | 0-10 | 10-20 | 20-30 | 30-40 | 40-50 | 50-60 |
| Frequency | 8 | 5 | 12 | 35 | 24 | 16 |
Using step-deviation method, calculate the mean marks of the following distribution.
| C.I. | 50 – 55 | 55 – 60 | 60 – 65 | 65 – 70 | 70 – 75 | 75 – 80 | 80 – 85 | 85 – 90 |
| Frequency | 5 | 20 | 10 | 10 | 9 | 6 | 12 | 8 |
A boy scored following marks in various class tests during a term; each test being marked out of 20.
15, 17, 16, 7, 10, 12, 14, 16, 19, 12 and 16
What are his median marks?
The marks of 200 students in a test were recorded as follows:
| Marks | No. of students |
| 10-19 | 7 |
| 20-29 | 11 |
| 30-39 | 20 |
| 40-49 | 46 |
| 50-59 | 57 |
| 60-69 | 37 |
| 70-79 | 15 |
| 80-89 | 7 |
Construct the cumulative frequency table. Drew the ogive and use it too find:
(1) the median and
(2) the number of student who score more than 35% marks.
In a case of 40 students, marks obtained by the students in a class test (out of 10) are given below:
| Marks | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 |
| Number of students | 1 | 2 | 3 | 3 | 6 | 10 | 5 | 4 | 3 | 3 |
Calculate the following for the given distribution:
(i) Median
(ii) Mode
Find the mean of the following frequency distribution :
| Class | 101-110 | 111-120 | 121-130 | 131-140 | 141-150 | 151-160 |
| Frequency | 11 | 16 | 20 | 30 | 14 | 9 |
The marks obtained by 200 students in an examination are given below :
| Marks | 0-10 | 10-20 | 20-30 | 30-40 | 40-50 | 50-60 | 60-70 | 70-80 | 80-90 | 90-100 |
| No.of students | 5 | 10 | 11 | 20 | 27 | 38 | 40 | 29 | 14 | 6 |
Using a graph paper, draw an Ogive for the above distribution. Use your Ogive to estimate:
(i) the median;
(ii) the lower quartile;
(iii) the number of students who obtained more than 80% marks in the examination and
(iv) the number of students who did not pass, if the pass percentage was 35.
Use the scale as 2 cm = 10 marks on one axis and 2 cm = 20 students on the other axis.
Estimate the median, the lower quartile and the upper quartile of the following frequency distribution by drawing an ogive:
| Marks (less than) | 10 | 20 | 30 | 40 | 50 | 60 | 70 | 80 |
| No. of students | 5 | 15 | 30 | 54 | 72 | 86 | 94 | 100 |
The mean of a certain number of observations is 32. Find the resulting mean, if the observation is, multiplied by 2
Find the median of 18, 19, 20, 23, 22, 20, 17, 19, 25 and 21
