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प्रश्न
The frequency distribution has been represented graphically as follows:
| Marks | 0 – 20 | 20 – 40 | 40 – 60 | 60 – 100 |
| Number of Students | 10 | 15 | 20 | 25 |
Do you think this representation is correct? Why?
उत्तर
No, here the widths of the rectangles are varying, so we need to make certain modifications in the length of the rectangles so that the areas are proportional to the frequencies.
We proceed as follows:
1. Select a class interval with the minimum class size, here the minimum class size is 20.
2. The length of the rectangles are then modified to be proportionate to the class size 20.
Now, we get the following modified table:
| Marks | Number of students (Frequency) |
Width of the class |
Length of the rectangle |
| 0 – 20 | 10 | 20 | `10/20 xx 20 = 10` |
| 20 – 40 | 15 | 20 | `15/20 xx 20 = 15` |
| 40 – 60 | 20 | 20 | `20/20 xx 20 = 20` |
| 60 – 100 | 25 | 40 | `25/40 xx 20 = 12.5` |
So, the correct histogram with varying width is given below:
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संबंधित प्रश्न
The length of 40 leaves of a plant are measured correct to one millimetre, and the obtained data is represented in the following table:-
| Length (in mm) | Number of leaves |
| 118 - 126 | 3 |
| 127 - 135 | 5 |
| 136 - 144 | 9 |
| 145 - 153 | 12 |
| 154 - 162 | 5 |
| 163 - 171 | 4 |
| 172 - 180 | 2 |
- Draw a histogram to represent the given data. [Hint: First make the class intervals continuous]
- Is there any other suitable graphical representation for the same data?
- Is it correct to conclude that the maximum number of leaves are 153 mm long? Why?
The runs scored by two teams A and B on the first 60 balls in a cricket match are given below:
| Number of balls | Team A | Team B |
| 1 - 6 | 2 | 5 |
| 7 - 12 | 1 | 6 |
| 13 - 18 | 8 | 2 |
| 19 - 24 | 9 | 10 |
| 25 - 30 | 4 | 5 |
| 31 - 36 | 5 | 6 |
| 37 - 42 | 6 | 3 |
| 43 - 48 | 10 | 4 |
| 49 - 54 | 6 | 8 |
| 55 - 60 | 2 | 10 |
Represent the data of both the teams on the same graph by frequency polygons.
[Hint: First make the class intervals continuous.]
The following table gives the route length (in thousand kilometres) of the Indian Railways in some of the years:
| Year | 1960-61 | 1970-71 | 1980-81 | 1990-91 | 2000-2001 |
| Route length (in thousand km) |
56 | 60 | 61 | 74 | 98 |
Represent the above data with the help of a bar graph.
The expenditure (in 10 crores of rupees) on health by the Government of India during the various five year plans is shown below:
| Plans: | I | II | III | IV | V | VI |
| Expenditure on health (in 10 crores of rupees) |
7 | 14 | 23 | 34 | 76 | 182 |
Construct a bar graph to represent the above data.
A frequency polygon is constructed by plotting frequency of the class interval and the
In the 'less than' type of ogive the cumulative frequency is plotted against
Draw frequency polygons for each of the following frequency distribution:
(a) using histogram
(b) without using histogram
|
C.I |
10 - 30 |
30 - 50 |
50 - 70 | 70 - 90 | 90 - 110 | 110 - 130 | 130 - 150 |
| ƒ | 4 | 7 | 5 | 9 | 5 | 6 | 4 |
Construct a frequency polygon for the following distribution:
| Class-intervals | 0-4 | 4 - 8 | 8 - 12 | 12 - 16 | 16 - 20 | 20 - 24 |
| Frequency | 4 | 7 | 10 | 15 | 11 | 6 |
Construct a combined histogram and frequency polygon for the following frequency distribution:
| Class-Intervals | 10 - 20 | 20 - 30 | 30 - 40 | 40 - 50 | 50 - 60 |
| Frequency | 3 | 5 | 6 | 4 | 2 |
The daily wages in a factory are distributed as follows:
|
Daily wages (in Rs.) |
125 - 175 |
175 - 225 |
225 - 275 |
275 - 325 |
325 - 375 |
|
Number of workers |
4 |
20 |
22 |
10 |
6 |
Draw a frequency polygon for this distribution.
