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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 age groups and the number of persons in the age groups, who donated blood in blood donation camp is given below. Find the measures of central angles to show the information by a pie diagram.
| Age group (Years) | 20-25 | 25-30 | 30-35 | 35-40 |
| No of persons | 80 | 60 | 35 | 25 |
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 |
Draw a histogram of the following data:
| Class interval: | 10−15 | 15−20 | 20−25 | 25−30 | 30−35 | 34−40 |
| Frequency: | 30 | 98 | 80 | 58 | 29 | 50 |
The following frequency distribution table shows marks obtained by 180 students in Mathematics examination.
| Marks | No. of students |
| 0 - 10 | 25 |
| 10 - 20 | x |
| 20 - 30 | 30 |
| 30 - 40 | 2x |
| 40 - 50 | 65 |
Find the value of x. Also draw a histogram representing the above information.
Construct histograms for following frequency distribution:
| Class Interval | 130-140 | 140-150 | 150-160 | 160-170 | 170-180 |
| Frequency | 24 | 16 | 29 | 20 | 11 |
Draw a histogram and frequency polygon to represent the following data (on the same scale) which shows the monthly cost of living index of a city in a period of 2 years:
| Cost of living Index | Number of months |
| 440 - 460 | 2 |
| 460 - 480 | 4 |
| 480 - 500 | 3 |
| 500 - 520 | 5 |
| 520 - 540 | 3 |
| 540 - 560 | 2 |
| 560 - 580 | 1 |
| 580 - 600 | 4 |
| Total | 24 |
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?
Histogram shows the number of people owning the different number of books. Answer the question based on it.
The number of people owning books more than 60 is ______.
Histogram shows the number of people owning the different number of books. Answer the question based on it.
The number of people having books more than 20 and less than 40 is ______.
Draw a histogram for the following data.
| Class interval | 10 – 15 | 15 – 20 | 20 – 25 | 25 – 30 | 30 – 35 | 35 – 40 |
| Frequency | 30 | 98 | 80 | 58 | 29 | 50 |
