# Mathematics Class 7 Chapter 3 – Data Handling – Exercise 3.3 – NCERT Exercise Solution

1. Use the bar graph (Fig 3.3) to answer the following questions.

(a) Which is the most popular pet?

(b) How many students have dogs as a pet?

Solution:

The given bar graph represents the pets owned by the students.

(a) From the given bar graph, the most popular pet is Cat. It is owned by 10 students out of 12 students.

(b) From the bar graph, 8 students have a dog as a pet out of 12 students.

2. Read the bar graph (Fig 3.4) which shows the number of books sold by a bookstore during five consecutive years and answer the following questions:

(i) About how many books were sold in 1989? 1990? 1992?

Solution:

By observing the given bar graph,

175 books were sold in the year 1989.

475 books were sold in the year 1990.

225 books were sold in the year 1992.

(ii) In which year were about 475 books sold? About 225 books sold?

Solution:

By observing the given bar graph,

475 books were sold in the year 1990.

225 books were sold in the year 1992.

(iii) In which years were fewer than 250 books sold?

Solution:

By observing the given bar graph,

In the years 1989 and 1992, the number of books sold was less than 250.

(iv) Can you explain how you would estimate the number of books sold in 1989?

Solution:

By observing the given bar graph,

The number of books sold in the year 1989 is about 1 and ¾th part of 1 cm.

WKT, Scale is taken as 1 cm = 100 books

= 100 + (¾ × 100)

= 100 + (3 × 25)

= 100 + 75

= 175

3. Number of children in six different classes are given below. Represent the data on a bar graph.

(a) How would you choose a scale?

Solution:

We will take the scale as 1 unit = 20 children.

(i) Which class has the maximum number of children? And the minimum?

Solution:

Class 5th has the maximum number of children i.e. 135 and class 7th has the minimum number of children i.e. 95.

(ii) Find the ratio of students of class sixth to the students of class eight.

Solution:

We have the total number of students in class 6th is 120 and the total number of students in class 8th is 100

Then,

The ratio between the number of students of class 6th and 8th,

= (120/100)

= 6/5

= 6: 5

4. The performance of a student in 1st Term and 2nd Term is given. Draw a double bar graph choosing appropriate scale and answer the following:

Solution:

(i) In which subject, has the child improved his performance the most?

Solution:

By observing the double bar graph, we observe that the maximum marks increase in the Maths subject. So, the child has improved his performance in Maths.

(ii) In which subject is the improvement the least?

Solution:

By observing the double bar graph, we observe that the improvement was the least in Social Science.

(iii) Has the performance gone down in any subject?

Solution:

By observing the double bar graph, we observe that the performance in Hindi has gone down.

5. Consider this data collected from a survey of a colony.

(i) Draw a double bar graph choosing an appropriate scale.

What do you infer from the bar graph?

Solution:

The above double bar graph represents the number of people who prefer either watching or participating in different sports. After observing the double bar graph, we came to conclude that most of the people like watching and participating in cricket while the least number of people like watching and participating in Athletics.

(ii) Which sport is most popular?

Solution:

By observing the double bar graph, we came to conclude that Cricket is the most popular sport.

(iii) Which is more preferred, watching or participating in sports?

Solution:

By observing the double bar graph, we came to conclude that watching sports has more preferred by people, rather than participating in sports.

6. Take the data giving the minimum and the maximum temperature of various cities given in the beginning of this Chapter (Table 3.1). Plot a double bar graph using the data and answer the following:

Solution:

(i) Which city has the largest difference in the minimum and maximum temperature on the given date?

Solution:

By observing the double bar graph, we observe that Jammu has the largest difference in the minimum and maximum temperature on 20.6.2006.

i.e 41o c – 26o c = 15o c

(ii) Which is the hottest city and which is the coldest city?

Solution:

By observing the double bar graph, we came to conclude that Jammu is the hottest city with a temperature of 41o c and Bengaluru is the coldest city with a temperature of 21o c

(iii) Name two cities where the maximum temperature of one was less than the minimum temperature of the other.

Solution:

By observing the double bar graph :

Bangalore and Jaipur, Bangalore and Ahmedabad. Bangalore has its maximum temperature was 28 o C, while the minimum temperature of both Ahmadabad and Jaipur was 29 o c.

(iv) Name the city which has the least difference between its minimum and the maximum temperature.

Solution:

By observing the double bar graph, we came to conclude that Mumbai has the least difference between its minimum and maximum temperature.

i.e. 32o c – 27o c = 5o c

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