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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
उत्तर
Short-cut method
|
Marks |
No. of boys |
Mid-value |
A = 65 |
fidi |
| 30 – 40 | 10 | 35 | –30 | –300 |
| 40 – 50 | 12 | 45 | –20 | –240 |
| 50 – 60 | 14 | 55 | –10 | –140 |
| 60 – 70 | 12 | A = 65 | 0 | 0 |
| 70 – 80 | 9 | 75 | 10 | 90 |
| 80 – 90 | 7 | 85 | 20 | 140 |
| 90 – 100 | 6 | 95 | 30 | 180 |
| Total | 70 | –270 |
`barx = A + (sumf_i d_i)/(sumf_i)`
= `65 + ((-270)/70)`
= 65 – 3.86
= 61.14
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संबंधित प्रश्न
For the following set of data, find the median:
10, 75, 3, 81, 17, 27, 4, 48, 12, 47, 9 and 15.
Find the mode and the median of the following frequency distributions.
| x | 10 | 11 | 12 | 13 | 14 | 15 |
| f | 1 | 4 | 7 | 5 | 9 | 3 |
Find the mean of all natural numbers from 32 to 46. Find the new mean when each number is diminished by 5.
The weights of 11 students in a class are 36 kg, 45 kg, 44 kg, 37 kg, 36 kg, 41 kg, 45 kg, 43 kg, 39 kg, 42 kg and 40 kg. Find the median of their weights.
The marks of 200 students in a test is given below :
| Marks% | 10-19 | 20-29 | 30-39 | 40-49 | 50-59 | 60-69 | 70-79 | 80-89 |
| No. of Students | 7 | 11 | 20 | 46 | 57 | 37 | 15 | 7 |
Draw an ogive and find
(i) the median
(ii) the number of students who scored more than 35% marks
The mean of five numbers is 27. If one number is excluded, the mean of the remaining numbers is 25. Find the excluded number.
Find the median of 18, 19, 20, 23, 22, 20, 17, 19, 25 and 21
Find the median of 21, 21, 22, 23, 23, 24, 24, 24, 24, 25 and 25
Find the mean and the median of: 2, 4, 5, 8, 10,13 and 14
The marks of 200 students in a test were recorded as follows:
| 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 | 7 | 11 | 20 | 40 | 52 | 36 | 15 | 9 | 5 |
Using graph sheet draw ogive for the given data and use it to find the,
- median,
- number of students who obtained more than 65% marks
- number of students who did not pass, if the pass percentage was 35.
