All exercise questions and the in-text activity from the NCERT textbook Practical Work in Geography, Part-II, Chapter 3, “Graphical Representation of Data”, exactly as the English edition prints them, with a full model answer for each. Try your own answer first, then check it against this one.
1 Choose the right answer from the four alternatives given below
Q. Which one of the following map shows the population distribution:
(a) Choropleth maps (b) Isopleth maps (c) Dot maps (d) Square root maps
Answer: (c) Dot maps. Dot maps are drawn specifically to show the distribution of phenomena such as population, cattle or crop types, using equal-size dots scaled to a chosen value, placed over administrative units. Choropleth maps show data tied to administrative units as a whole (like density or literacy rate) rather than raw distribution; isopleth maps join places of equal value on natural boundaries; “square root maps” is not a map type this chapter teaches.
Q. Which one of the following is best suited to represent the decadal growth of population:
(a) Line graph (b) Bar diagram (c) Circle diagram (d) Flow diagram
Answer: (a) Line graph. The chapter’s own rule for selecting a method says that data related to the temperature or growth of population between different periods in time may best be represented using line graphs, while bar diagrams are suited best for rainfall or the production of commodities. The chapter’s Example 3.1 draws India’s population growth rate, 1901-2011, exactly this way, as a line graph.
Q. Polygraph is constructed to represent:
(a) Only one variable (b) Two variables only (c) More than two variables (d) None of the above
Answer: (c) More than two variables. The chapter defines a polygraph as a line graph in which two or more than two variables are shown by an equal number of lines for an immediate comparison; among the four given options, “more than two variables” is the answer that best matches this “two or more” definition.
Q. Which one of the following maps is known as “Dynamic Map”?
(a) Dot map (b) Choropleth (c) Isopleth (d) Flow map
Answer: (d) Flow map. The chapter states that a flow chart/map, being a combination of graph and map used to show the flow of commodities or people between origin and destination, is also called a Dynamic Map.
2 Answer the following questions in about 30 words
Q. What is a thematic map?
Answer: A thematic map (also called a distribution map) is a map drawn to show the regional pattern of a specific theme, such as population, literacy or rainfall, using state or district-level data, an outline administrative map, and a suitable physical map of the region.
Q. Differentiate between multiple bar diagram and compound bar diagram.
Answer: A multiple bar diagram represents two or more variables using separate, adjacent bars placed next to each other for comparison. A compound bar diagram instead shows the different components of one variable (or different variables of one component) as segments within a single bar, with the total bar length divided proportionally.
Q. What are the requirements to construct a dot map?
Answer: A dot map needs an administrative map showing state/district/block boundaries, statistical data for the chosen theme in those units, a scale to fix the value of one dot, and a physiographic/relief map of the region to guide dot placement in difficult terrain.
Q. Describe the method of constructing a traffic flow map.
Answer: An outline map showing the routes and nodal stations is prepared first. A scale is chosen to convert the flow quantity (such as number of trains) into a proportional strip width, and this thickness is plotted along each route. The map is completed with a terraced-scale legend showing the width for each quantity band.
Q. What is an Isopleth map? How an interpolation is carried out?
Answer: An isopleth map joins places of equal value (such as temperature or rainfall) with an imaginary line, drawn on natural rather than administrative boundaries. Interpolation, the insertion of intermediate values between two known points, is carried out using the formula: (Distance between the two points ÷ Difference between their values) × Interval.
Q. Describe and illustrate important steps to be followed in preparing a choropleth map.
Answer: The data are arranged in ascending or descending order, then grouped into five categories (very low to very high). The interval between categories is calculated as Range ÷ 5 (Range = Maximum − Minimum), and this interval is added successively from the minimum value to fix each band. Finally, shades or colours are assigned to the categories in increasing or decreasing order on the administrative-unit map.
Q. Discuss important steps to represent data with help of a pie-diagram.
Answer: A suitable radius (3-5 cm) is chosen and a line is drawn from the centre to the arc as a reference radius. Each category’s percentage is converted to an angle (Percentage × 3.6, or Value/Total × 360), and the angles are measured from the arc in ascending order, clockwise, starting with the smallest, to avoid accumulating error. The diagram is completed with a title, sub-title and legend using distinct shades for each category.
3 Activity
The book’s Activity section asks for five diagrams to be drawn from given data. In the exam the diagram is drawn on graph paper; below, each answer names the suitable diagram, gives the scale and the worked figures you need, lists the drawing steps, and ends with a model diagram (except the two maps in Activity 4, which need an outline map of India).
Q. Represent the following data with the help of suitable diagram. India : Trends of Urbanisation 1901-2001 (decennial growth %: 1911 0.35, 1921 8.27, 1931 19.12, 1941 31.97, 1951 41.42, 1961 26.41, 1971 38.23, 1981 46.14, 1991 36.47, 2001 31.13).
Answer: Suitable diagram: a line graph. The chapter says growth of population between different periods in time is best represented by a line graph. Steps: (a) round the values, e.g. 0.35 to 0.4, 8.27 to 8.3, 46.14 to 46.1; (b) mark the years 1911 to 2001 at equal intervals on the X-axis; (c) take a scale of 1 cm = 5 per cent on the Y-axis, from 0 to 50 (no value is negative, so no negative range is needed); (d) plot each decade’s value as a dot and join the dots with a free-hand line; (e) add the title “India: Trends of Urbanisation, 1901-2001”. The graph rises to a peak of 46.14 per cent in 1981, after dips in 1961 (26.41) and 1991 (36.47).
Q. Represent the following data with the help of suitable diagram. India : Literacy and Enrolment Ratio in Primary and Upper Primary Schools (1950-51 and 1999-2000).
Answer: Suitable diagram: a multiple bar diagram, because several related variables are compared for the same two years, as in the chapter’s Example 3.5 (literacy rate: total, male, female). Draw three groups of bars for each year: literacy ratio (person 18.3, male 27.2, female 8.86 in 1950-51; 65.4, 75.8, 54.2 in 1999-2000), primary enrolment ratio (boys 60.6, girls 25, total 42.6; then 104, 85, 94.9) and upper primary enrolment ratio (boys 20.6, girls 4.6, total 12.7; then 67.2, 50, 58.8). Use a Y-axis scale of 1 cm = 10 (0 to 110, since one value is 104), keep all bars of equal width, and shade each variable differently with a legend.
Q. Represent the following data with help of pie-diagram. India : Land use 1951-2001 (1950-51 and 1998-2001).
Answer: Draw two pie diagrams, one for each year, with the same radius (say 4 cm). The values are percentages, so each angle = percentage × 3.6.
| Land use | 1950-51 (%) | Angle | 1998-2001 (%) | Angle |
|---|---|---|---|---|
| Net Sown Area | 42 | 151.2° | 46 | 165.6° |
| Forest | 14 | 50.4° | 22 | 79.2° |
| Not available for cultivation | 17 | 61.2° | 14 | 50.4° |
| Fallow Land | 10 | 36.0° | 8 | 28.8° |
| Pasture and Tree | 9 | 32.4° | 5 | 18.0° |
| Culturable Waste Land | 8 | 28.8° | 5 | 18.0° |
| Total | 100 | 360° | 100 | 360° |
Measure the angles clockwise in ascending order, starting with the smallest, and finish each circle with its title and a common legend.
Q. Study the table given below (Area and Production of Rice in major States) and draw the given diagrams/maps: (a) Construct a multiple bar diagram to show area under rice in each State. (b) Construct a pie-diagram to show the percentage of area under rice in each State. (c) Construct a dot map to show the production of rice in each State. (d) Construct a Choropleth map to show the percentage of production of rice in States.
Answer: (a) Multiple bar diagram: for each State draw two adjacent bars, area in thousand hectares (West Bengal 5,435; Uttar Pradesh 5,839; Andhra Pradesh 4,028; Punjab 2,611; Tamil Nadu 2,113; Bihar 3,671) and its production in thousand tonnes (12,428; 11,540; 12,428; 9,154; 7,218; 5,417), both on one scale such as 1 cm = 2,000 thousand. (The percentage columns are in a different unit, so they are not drawn on the same axis as these bars.)
(b) Pie diagram of the percentage of area (angle = % × 3.6). The six States together have 53.6 per cent of the area, so the remaining 46.4 per cent is shown as “Other States”: West Bengal 12.3 → 44.3°; Uttar Pradesh 13.2 → 47.5°; Andhra Pradesh 9.1 → 32.8°; Punjab 5.9 → 21.2°; Tamil Nadu 4.8 → 17.3°; Bihar 8.3 → 29.9°; Other States 46.4 → 167.0°; total 360°.
(c) Dot map of production: choose a dot value, for example 1 dot = 2,00,000 tonnes (200 thousand tonnes). Dots = production ÷ 200: West Bengal 12,428 → 62.1 → 62 dots; Uttar Pradesh 11,540 → 57.7 → 58; Andhra Pradesh 12,428 → 62.1 → 62; Punjab 9,154 → 45.8 → 46; Tamil Nadu 7,218 → 36.1 → 36; Bihar 5,417 → 27.1 → 27. Place equal-size dots within each State on an outline map, fewer in hilly or desert parts.
(d) Choropleth map of the percentage of production: arrange the values (6.4, 8.5, 10.8, 13.5, 13.6, 14.6); Range = 14.6 − 6.4 = 8.2; interval = 8.2 ÷ 5 = 1.64. Categories: 6.40-8.04 very low (Bihar); 8.04-9.68 low (Tamil Nadu); 9.68-11.32 medium (Punjab); 11.32-12.96 high (no State); 12.96-14.60 very high (Andhra Pradesh, Uttar Pradesh, West Bengal). Shade the categories from light to dark and add the legend. (The table prints the same production figure, 12,428, for West Bengal and Andhra Pradesh but different percentages; use the percentage column for this map, as the question asks.)
Q. Show the following data of temperature and rainfall of Kolkata with a suitable diagram.
Answer: Suitable diagram: a line and bar graph, as in the chapter’s Example 3.4 for Delhi. Divide the X-axis into 12 months. Show rainfall as bars on the left Y-axis with a scale of 1 cm = 5 cm of rainfall (0 to 35, since the highest is 33.4 cm in August), and temperature as a line on the right Y-axis with a scale of 1 cm = 5°C (0 to 35, since the highest is 30.4°C in May). The diagram shows the temperature peak in May, just before the monsoon, and the rainfall peak in July-August (33.1 and 33.4 cm).
4 In-text Activity (asked within the chapter)
In-text Activity. Find out the reasons for sudden change in population between 1911 and 1921 as shown in Fig. 3.2.
Answer: Fig. 3.2 shows India’s growth rate falling from 0.56 per cent (1911) to −0.30 per cent (1921), the only negative value in Table 3.1, so the population actually decreased in that decade. The main reasons were very high death rates: the influenza epidemic of 1918-19 killed millions of people in India, and famines and epidemics such as plague, malaria and cholera also took a heavy toll in these years. Because deaths exceeded births, the population growth became negative.