Advertisements
Advertisements
Question
The distribution of heights (in cm) of 96 children is given below. Construct a histogram and a frequency polygon on the same axes.
| Height (in cm): | 124 to 128 |
128 to 132 |
132 to 136 |
136 to 140 |
140 to 144 |
144 to 148 |
148 to 152 |
152 to 156 |
156 to 160 |
160 to 164 |
| No. of Children: | 5 | 8 | 17 | 24 | 16 | 12 | 6 | 4 | 3 | 1 |
Advertisements
Solution
To represent the given data by a histogram, we first draw horizontal and vertical axes. Let us consider that the horizontal and vertical axes represent the class-limits and the frequencies of the class-intervals respectively.
The given data is a continuous grouped frequency distribution with equal class-intervals. Construct rectangles with class-intervals as bases and respective frequencies as heights.
To draw the frequency polygon of the given data using histogram, obtain the mid-points of the upper horizontal side of each rectangle and then join these mid-points of the adjacent rectangles of the histogram by line segments. Obtain the mid-points of two class-intervals of 0 frequencies, i.e. on the horizontal axis, one adjacent to the first, on its left and one adjacent to the last, on its right. These class-intervals are known as imagined class-intervals. Complete the polygon by joining the mid-points of first and last class-intervals to the mid-points of imagined class-intervals adjacent to them. Let us take one vertical division is equal to 4.
The heights of the different rectangles are as following
1. The height of the rectangle corresponding to the class-interval 124-128 is `5/4 = 1.25` big divisions.
2. The height of the rectangle corresponding to the class-interval 128-132 is ` 8/4`=2` big divisions.
3. The height of the rectangle corresponding to the class-interval 132-136 is `17/4 = 4.25` big divisions.
4. The height of the rectangle corresponding to the class-interval 136-140 is `24/4 = 6` big divisions.
5. The height of the rectangle corresponding to the class-interval 140-144 is `16/4 = 4` big divisions.
6. The height of the rectangle corresponding to the class-interval 144-148 is `12/4 = 3` big divisions.
7. The height of the rectangle corresponding to the class-interval 148-152 is `6/4 = 1.5` big divisions.
8. The height of the rectangle corresponding to the class-interval 152-156 is `4/4 =1 ` big divisions.
9. The height of the rectangle corresponding to the class-interval 156-160 is `3/4 = 0.75` big divisions.
10. The height of the rectangle corresponding to the class-interval 160-164 is `1/4 = 0.25 ` big divisions.
The histogram and frequency polygon of the given data is the following:
APPEARS IN
RELATED QUESTIONS
Read the bar graph given in Fig. 23.21 and answer the following questions:
(i) What is the information given by the bar graph?
(ii) What is the number of families having 6 members?
(iii) How many members per family are there in the maximum number of families? Also tell the number of such families.
(iv) What are the number of members per family for which the number of families are equal? Also, tell the number of such families?
Read the bar graph given in Fig. 23.22 and answer the following questions:
(i) What information is given by the bar graph?
(ii) Which Doordarshan centre covers maximum area? Also tell the covered area.
(iii) What is the difference between the areas covered by the centres at delhi and Bombay?
(iv) Which Doordarshan centres are in U.P State? What are the areas covered by them?
The production of saleable steel in some of the steel plants our country during 1999 is given below:
| Plant | Bhilai | Durgapur | Rourkela | Bokaro |
| Production (In thousand tonnes) |
160 | 80 | 200 | 150 |
Construct a bar graph to represent the above data on a graph paper by using the scale 1 big divisions = 20 thousand tonnes.
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 following data shows the average age of men in various countries in a certain year:
| Country | India | Nepal | China | Pakistan | U.K | U.S.A |
| Average age (in years) |
55 | 52 | 60 | 50 | 70 | 75 |
Represent the above information by a bar graph.
The following data gives the amount of manure (in thousand tonnes) manufactured by a company during some years:
| Year | 1992 | 1993 | 1994 | 1995 | 1996 | 1997 |
| Manure (in thousand tonnes) |
15 | 35 | 45 | 30 | 40 | 20 |
(i) Represent the above data with the help of a bar graph.
(ii) Indicate with the help of the bar graph the year in which the amount of manufactured by the company was maximum.
(iii) Choose the correct alternative:
The consecutive years during which there was maximum decrease in manure production are:
(a) 1994 and 1995
(b) 1992 and 1993
(c) 1996 and 1997
(d) 1995 and 1996
The birth rate thousand of the following states over a certain period is given below:
| States | Punjab | Haryana | U.P. | Gujarat | Rajasthan | Jammu and Kashmir |
| Birth Rate (per thousand ) | 22.9 | 21.8 | 19.5 | 21.1 | 23.9 | 18.3 |
Draw a bar graph for the above data.
Is it correct to say that in a histogram, the area of each rectangle is proportional to the class size of the corresponding class interval? If not, correct the statement.
Expenditure on Education of a country during a five year period (2002-2006), in crores of rupees, is given below:
| Elementary education | 240 |
| Secondary Education | 120 |
| University Education | 190 |
| Teacher’s Training | 20 |
| Social Education | 10 |
| Other Educational Programmes | 115 |
| Cultural programmes | 25 |
| Technical Education | 125 |
Represent the information above by a bar graph.
Draw a histogram to represent the following grouped frequency distribution:
| Ages (in years) | Number of teachers |
| 20 – 24 | 10 |
| 25 – 29 | 28 |
| 30 – 34 | 32 |
| 35 – 39 | 48 |
| 40 – 44 | 50 |
| 45 – 49 | 35 |
| 50 – 54 | 12 |
