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प्रश्न
The histogram below represents the scores obtained by 25 students in a mathematics mental test. Use the data to:
- Frame a frequency distribution table.
- To calculate mean.
- To determine the Modal class.
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उत्तर
i.
| Class interval | Frequency |
| 0 – 10 | 2 |
| 10 – 20 | 5 |
| 20 – 30 | 8 |
| 30 – 40 | 4 |
| 40 – 50 | 6 |
ii.
| Class interval | Frequency (f) | Mean value (x) | fx |
| 0 – 10 | 2 | 5 | 10 |
| 10 – 20 | 5 | 15 | 75 |
| 20 – 30 | 8 | 25 | 200 |
| 30 – 40 | 4 | 35 | 140 |
| 40 – 50 | 6 | 45 | 270 |
| `sumf = 25` | `sumf = 695` |
∴ Mean = `(sumfx)/(sumf)`
= `695/25`
= 27.8
iii. Here the maximum frequency is 8 which is corresponding to class 20 – 30.
Hence, the modal class is 20 – 30.
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संबंधित प्रश्न
The weekly wages (in Rs) of 30 workers in a factory are.
830, 835, 890, 810, 835, 836, 869, 845, 898, 890, 820, 860, 832, 833, 855, 845, 804, 808, 812, 840, 885, 835, 835, 836, 878, 840, 868, 890, 806, 840
Using tally marks make a frequency table with intervals as 800 − 810, 810 − 820 and so on.
Draw histogram for the following frequency distributions:
| Class Marks | 16 | 24 | 32 | 40 | 48 | 56 | 64 |
| Frequency | 8 | 12 | 15 | 18 | 25 | 19 | 10 |
The following table is based on the marks of the first term examination of 10th class students. Show the information by a histogram. Also, draw a frequency polygon with the help of the histogram.
| Class-mark of marks | 325 | 375 | 425 | 475 | 525 | 575 |
| No. of students | 25 | 35 | 45 | 40 | 32 | 20 |
The weekly wages (in Rs.) of 30 workers in a factory are given:
830, 835, 890, 810, 835, 836, 869, 845, 898, 890, 820, 860, 832, 833, 855, 845, 804, 808, 812, 840, 885, 835, 835, 836, 878, 840, 868, 890, 806, 840
Mark a frequency table with intervals as 800-810, 810-820 and so on, using tally marks. Also, draw a histogram and answer the following questions:
(i) Which group has the maximum number of workers?
(ii) How many workers earn Rs 850 and more?
(iii) How many workers earn less than Rs 850?
Construct histograms for following frequency distribution:
| Class Mark | 6 | 12 | 18 | 24 | 30 | 36 |
| Frequency | 8 | 12 | 15 | 18 | 25 | 7 |
Construct histograms for following frequency distribution:
| Class Interval | 1-10 | 11-20 | 21-30 | 31-40 | 41-50 |
| Frequency | 11 | 23 | 30 | 20 | 16 |
The marks obtained by 50 students in Mathematics are given below.
(i) Make a frequency distribution table taking a class size of 10 marks
(ii) Draw a histogram and a frequency polygon.
| 52 | 33 | 56 | 52 | 44 | 59 | 47 | 61 | 49 | 61 |
| 47 | 52 | 67 | 39 | 89 | 57 | 64 | 58 | 63 | 65 |
| 32 | 64 | 50 | 54 | 42 | 48 | 22 | 37 | 59 | 63 |
| 36 | 35 | 48 | 48 | 55 | 62 | 74 | 43 | 41 | 51 |
| 08 | 71 | 30 | 18 | 43 | 28 | 20 | 40 | 58 | 49 |
Draw a histogram for the following data.
| Mid Value (x) | 15 | 25 | 35 | 45 | 55 | 65 | 75 |
| Frequency (f) | 12 | 24 | 30 | 18 | 26 | 10 | 8 |
Try yourself
- Next time when you watch your favourite TV programme, count the number of advertisements during each break. Use tally marks. Put a dot below the tally when you find children in any advertisement.
- Compare with your friends. Do you get different answers?
The below histogram shows the number of literate females in the age group of 10 to 40 years in a town.
- Write the classes assuming all the classes are of equal width.
- What is the classes width?
- In which age group are literate females the least?
- In which age group is the number of literate females the highest?
