Important Questions Class 8 Maths Chapter 15: Introduction to Graphs

Important questions with solutions for Class 8 Maths Chapter 15 (Introduction to Graphs) has been provided here by our subject experts. The extra questions are available here to help students score better marks in final exam 2020. The materials provided at BYJU’S for CBSE students are as per the latest syllabus and in reference with NCERT book.

In this chapter, students will go through plotting the graph for the different given situations. For example, change in temperature with respect to the number of days can be plotted in an XY plane. The problems and solutions for graphs will consist of such scenarios. To prepare for Maths exam practice Class 8 Maths Important questions for all the chapters here.

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Important Questions With Solutions For Maths Class 8 Chapter 15 (Introduction to Graphs)

Q.1: The following line graph shows the yearly sales figures for a manufacturing company.

(a) What were the sales in (i) 2002 (ii) 2006?

(b) What were the sales in (i) 2003 (ii) 2005?

(c) Compute the difference between sales in 2002 and 2006.

(d) In which year was there the greatest difference between the sales as compared to its previous year?

Class 8 Maths Chapter 15 Introduction to Graphs 01

Solution:

(a) The sales in (i) 2002 were Rs. 4 crores and (ii) 2006 was Rs. 8 crores

(b) The sales in (i) 2003 was Rs. 7 crores and (ii) 2005 was Rs.10 crores.

(c) The difference of sales in 2002 and 2006 = Rs. 8 crores – Rs. 4 crores = Rs. 4 crores

(d) In the year 2005, there was the greatest difference between the sales and compared to its previous year, which is (Rs. 10 crores – Rs. 6 crores) = Rs. 4 crores.

Q.2: Use the tables below to draw linear graphs:

(a) The number of days a hillside city received snow in different years.

Year 2003 2004 2005 2006
Days 8 10 5 12

(b)Population (in thousands) of men and women in a village in different years.

Year 2003 2004 2005 2006 2007
No. of men 12 12.5 13 13.2 13.5
No. of women 11.3 11.9 13 13.6 12.8

Solution:

a) Consider “Years” along the x-axis and “Days” along the y-axis. Using the given information, the linear graph will look like:

Class 8 Maths Chapter 15 Introduction to Graphs 02

b) Consider “Years” along the x-axis and “No. of Men and No. of Women” along the y-axis (2 graphs). Using the given information, the linear graph will look like:

Class 8 Maths Chapter 15 Introduction to Graphs 03

Q.3: Plot the point (4, 3) on a graph sheet. Is it the same as the point (3, 4)?

Solution:

Locate the x, y axes, (they are actually number lines!). Start at O (0, 0). Move 4 units to the right; then move 3 units up, you reach the point (4, 3). From Fig 15.13, you can see that the points (3, 4) and (4, 3) are two different points.

Class 8 Maths Chapter 15 Introduction to Graphs 04

Q.4: Plot the following points on a graph sheet. Verify if they lie on a line:

(a) A(4,0), B(4, 2),C(4,6), D(4, 2.5)

(b) P(1, 1), Q(2, 2), R(3,3), S(4, 4)

(c) K(2, 3), L(5, 3), M(5,5), N(2, 5)

Solution:

Plot all the points on the graph.

Class 8 Maths Chapter 15 Introduction to Graphs 05

(a) All points A, B, C and D lie on a vertical line.

(b) P, Q, R and S points also make a line. It verifies that these points lie on a line.

(c) Points K, L, M and N do not lie in a straight line

Q.5: Draw the line passing through (2,3) and (3,2). Find the coordinates of the points at which this line meets the x-axis and y-axis.

Solution:

Graph for the Line passes through points (2, 3) and (3, 2) is:

Class 8 Maths Chapter 15 Introduction to Graphs 06

The coordinates of the points at which this line meets the x-axis at (5, 0) and Y axis at (0, 5).

Q.6: Draw the graphs for the following table of values, with suitable scales on the axes.

Interest on deposits for a year.

Deposit (in Rs.) 1000 2000 3000 4000 5000
Simple interest (in Rs.) 80 160 240 320 400

 

(i) Does the graph pass through the origin?

(ii) Use the graph to find the interest on Rs 2500 for a year.

(iii) To get an interest of Rs. 280 per year, how much money should be deposited?

Solution:

Represent “Deposit” on y-axis and “simple interest” on x-axis.

Class 8 Maths Chapter 15 Introduction to Graphs 07

(i) Yes, the graph passes through the origin.

(ii) Interest on Rs. 2500 is Rs. 200 for a year.

(iii) Rs. 3500 should be deposited for the interest of Rs. 280

Extra Questions For Class 8 Maths Chapter 15

    1. Plot the following points and verify if they lie on a line. If they lie on a line, name it.

(i) (0, 2), (0, 5), (0, 6), (0, 3.5)

(ii) A (1, 1), B (1, 2), C (1, 3), D (1, 4)

(iii) K (1, 3), L (2, 3), M (3, 3), N (4, 3)

(iv) W (2, 6), X (3, 5), Y (5, 3), Z (6, 2)

    1. State whether True or False. Correct that is false.

(i) A point whose x coordinate is zero and y-coordinate is non-zero will lie on the y-axis.

(ii) A point whose y coordinate is zero and x-coordinate is 5 will lie on y-axis.

(iii) The coordinates of the origin are (0, 0)

    1. A bank gives 10% Simple Interest (S.I.) on deposits by senior citizens. Draw a graph to illustrate the relation between the sum deposited and simple interest earned. Find from your graph

(a) the annual interest obtainable for an investment of ` 250.

(b) the investment one has to make to get an annual simple interest of ` 70.

    1. Draw a graph for the following.
Side of the square(in cm) 2 3 3.5 5 6
Perimeter (in cm) 8 12 14 20 24

Is it a linear graph?

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