NCERT Solutions for Class 8 Maths - Data Handling (Exercise 3.3 and 3.4)

Exercise 3.3 

Q1. Use the bar graph (fig 3.3) to answer the following questions:

(a) Which is the most popular pet? 
(b) How many students have dog as a pet? 

Ans: (a) Cat is the most popular pet.
(b) 8 students have dog as a pet.

Q2. Read the bar graph 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? 
(ii) In which year were about 475 books sold? About 225 books sold? 
(iii) In which years were fewer than 250 books sold? 
(iv) Can you explain how you would estimate the number of books sold in 1989? 

Ans: According to the given bar graph,
(i) (a) In 1989, 180 books were sold.
(b) In 1990, 475 books were sold.
(c) In 1992, 225 books were sold.
(ii) In 1990, about 475 books were sold and in 1992, about 225 books were sold.
(iii) In 1989 and 1992 fewer than 250 books were sold.
(iv) By reading the graph, we calculate that 180 books were sold in 1989.

Q3. Number of children in six different classes are given below. Represent the data on a bar graph. 

(a) How would you choose a scale? 
(b) Answer the following questions. 
(i) Which class has the maximum number of children? And the minimum? 
(ii) Find the ratio of students of class sixth to the students of class eight.

Ans: Data represented by the bar graph is as follows:

(a) Scale: 1 unit = 25 children
(b) (i) Fifth class has the maximum number of children and
Tenth class has the minimum number of children.

= 120/100
= 6/5 = 6:5

Q4. The performance of a student in 1^st term and 2^nd term is given. Draw a double bar graph choosing appropriate scale and answer the following: 

(i) In which subject has the child improved his performance the most? 
(ii) In which subject is the improvement the least? 
(iii) Has the performance gone down in any subject? 

Ans: Data represented by bar graph is as follows:

Difference of marks of 1^st term and 2^nd term
English = 70 – 67 = 3
Hindi = 65 – 72 = -7
Maths = 95 – 88 = 7
Science = 85 – 81 = 4
S. Science = 75 – 73 = 2
(i) He has most improved in Maths subject.
(ii) In S. Science subject, his improvement is less.
(iii) Yes, in Hindi subject, his performance has gone down.

Q5. 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? 
(ii) Which sport is most popular?
(iii) Which is more preferred, watching or participating in sports? 

Ans: Data represented by the double bar graph is as follows:

(i) This bar graph represents the number of persons who are watching and participating in their favourite sports.
(ii) Cricket is most popular.
(iii) Watching sports is more preferred.

Q6. Take the data giving the minimum and the maximum temperature of various cities given in the beginning of this Chapter. Plot a double bat graph using the data and answer the following: 
Temperature of Cities as on 20.6.2006

(i) Which city has the largest difference in the minimum and maximum temperature on the given data? 
(ii) Which is the hottest city and which is the coldest city? 
(iii) Name two cities where maximum temperature of one was less than the minimum temperature of the order. 
(iv) Name the city which has the least difference between its minimum and the maximum temperature. 

Ans: Data represented by double bar graph is as follows:

(i) Jammu has the largest difference in temperature i.e.,
Maximum temperature = 41^oC and
Minimum temperature = 26^oC.
∴ Difference = 41^oC – 26^oC = 15^oC
(ii) Jammu is the hottest city due to maximum temperature is high and Bangalore is the coldest city due to maximum temperature is low.
(iii) Maximum temperature of Bangalore is 28^oC
Minimum temperature of two cities whose minimum temperature is higher than the maximum temperature of Bangalore are Ahemedabad and Jaipur where the minimum temperature is 29^oC
(iv) Mumbai has the least difference in temperature i.e.,
Maximum temperature = 32^oC and
Minimum temperature = 27^oC
∴ Difference = 32^oC – 27^oC = 5^oC

Exercise 3.4 (Old Syllabus Questions)

Ques 1: Tell whether the following is certain to happen, impossible can happen but not certain. 
(i) You are older today than yesterday. 
(ii) A tossed coin will land heads up. 
(iii) A die when tossed shall land up with 8 on top. 
(iv) The next traffic light seen will be green. 
(v) Tomorrow will be a cloudy day. 
Ans: 
(i) It is certain to happen.
(ii) It can happen but not certain.
(iii) It is impossible.
(iv) It can happen but not certain.
(v) It can happen but not certain.

Ques 2: There are 6 marbles in a box with numbers from 1 to 6 marked on each of them. 
(i) What is the probability of drawing a marble with number 2? 
(ii) What is the probability of drawing a marble with number 5? 
Ans: Total marbles from 1 to 6 marked in a box = 6
(i) The probability of drawing a marble with number 2.
⇒ P (drawing one marble) = 1/6
(ii) The probability of drawing a marble with number 5.
⇒ P (drawing one marble) = 1/6

Ques 3: A coin is flipped to decide which team starts the game. What is the probability that your team will start? 
Ans: A coin has two possible outcomes Head and Tail.
Probability of getting Head or Tail is equal.
∴ P (Starting game) = 1/2