NCERT Solutions for Class 8 Maths Chapter 15: Introduction to Graphs - Exercise 15.3

Exercise 15.3

1. Draw the graphs for the following tables of values, with suitable scales on the axes:

(a) Cost of apples

Ans: Take the number of apples on the x-axis and cost on the y-axis. Take scale for x-axis as \[{\text{1 unit}} = 1{\text{ apple}}\] and for y-axis as \[{\text{1 unit}} = 5{\text{ rupees}}\].

Now plot the points \[{\text{(1,5),(2,10),(3,15),(4,20)}}\]and \[{\text{(5,25)}}\]to get the number of apples-cost linear graph:

(b) Distance travelled by a car

Ans: Take time on x-axis and distance travelled on  y-axis. Take scale for x-axis as \[{\text{1 unit}} = 1{\text{ hour}}\]and for y-axis as\[{\text{1 unit}} = 40{\text{ km}}\].

Now plot the points \[{\text{(6,40),(7,80),(8,120)}}\]and \[{\text{(9,160)}}\]to get the time-distance linear graph:

(i) How much distance did the car cover during the period 7.30 a.m. to 8 a.m.?

Ans: \[{\text{Distance travelled by 7:30 a}}{\text{.m}}{\text{. }} = 100{\text{ km}}\]

\[{\text{Distance travelled by 8 a}}{\text{.m}}{\text{. }} = 120{\text{ km}}\]

\[{\text{Distance travelled by the car during the period 7:30 a}}{\text{.m}}{\text{. to 8 a}}{\text{.m}}{\text{.}} = {\text{Distance travelled till 8 a}}{\text{.m}}{\text{.}} - {\text{Distance travelled till 7:30 a}}{\text{.m}}{\text{.}}\]

\[{\text{Distance travelled by the car during the period 7:30 a}}{\text{.m}}{\text{. to 8 a}}{\text{.m}}{\text{.}} = 120{\text{ km}} - 100{\text{ km}}\]

\[{\text{Distance travelled by the car during the period 7:30 a}}{\text{.m}}{\text{. to 8 a}}{\text{.m}}{\text{.}} = 20{\text{ km}}\]

Thus, the car covers 20 km during the period 7:30 a.m. to 8 a.m.

(ii) What was the time when the car had covered a distance of 100 km since its start?

Ans: At 7:30 a.m. , the car had covered a distance of 100 km since it’s start.

(c) Interest on deposits for a year:

Ans: Take deposit on x-axis and simple interest on  y-axis. Take scale for x-axis as \[{\text{1 unit}} = 1000{\text{ Rs}}\]and for y-axis as\[{\text{1 unit}} = 80{\text{ Rs}}\].

Now plot the points \[{\text{(1000,80),(2000,160),(3000,240),(4000,320)}}\]and \[{\text{(5000,400)}}\]to get the time-distance linear graph:

(i) Does the graph pass through the origin? 

Ans: From the graph, one can observe that the graph passes through the origin.

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

Ans: Rs2500 lies in between Rs 2000 and Rs 3000, therefore interest on Rs 2500 lies right in the middle of Rs 160 and Rs 240, i.e., Rs 200.

Thus, interest on Rs 2500 for a year is 200.

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

Ans: Rs 280 lies right in the middle of Rs 240 and Rs 320, therefore deposit with respect to it lies right in the middle of Rs 3000 and Rs 4000, i.e., Rs 3500.

Thus, to get an interest of Rs 280 per year, Rs 3500 must be deposited.

2. Draw a graph for the following:

(i)

Ans: Take sides of a square(in cm) on x-axis and perimeter(in cm) on  y-axis. Take scale for x-axis as \[{\text{1 unit}} = 1{\text{ cm}}\]and for y-axis as\[{\text{1 unit}} = 4{\text{ cm}}\].

Now plot the points \[{\text{(2,8),(3,12),(3}}{\text{.5,14),(5,20)}}\]and \[{\text{(6,24)}}\]to get the side-perimeter linear graph of a square:

Is it a linear graph?

Ans: The line  graph is a straight line, therefore it is a linear graph.

(ii)

Ans: Take sides of a square(in cm) on x-axis and area(in \[c{m^2}\]) on  y-axis. Take scale for x-axis as \[1{\text{ unit}} = 1{\text{ cm}}\]and for y-axis as\[1{\text{ unit}} = 4{\text{ c}}{{\text{m}}^2}\].

Now plot the points \[{\text{(2,4),(3,9),(4,16),(5,25)}}\]and \[{\text{(6,36)}}\]to get the side-area linear graph of a square:

Is it a linear graph?

Ans: The line graph is not a straight line, therefore it is not a linear graph.

NCERT Solutions for Class 8 Maths Chapter 15 Introduction to Graphs Exercise 15.3

Opting for the NCERT solutions for Ex 15.3 Class 8 Maths is considered as the best option for the CBSE students when it comes to exam preparation. This chapter consists of many exercises. Out of which we have provided the Exercise 15.3 Class 8 Maths NCERT solutions on this page in PDF format. You can download this solution as per your convenience or you can study it directly from our website/ app online.

Vedantu in-house subject matter experts have solved the problems/ questions from the exercise with the utmost care and by following all the guidelines by CBSE. Class 8 students who are thorough with all the concepts from the Subject Introduction to Graphs textbook and quite well-versed with all the problems from the exercises given in it, then any student can easily score the highest possible marks in the final exam. With the help of this Class 8 Maths Chapter 15 Exercise 15.3 solutions, students can easily understand the pattern of questions that can be asked in the exam from this chapter and also learn the marks weightage of the chapter. So that they can prepare themselves accordingly for the final exam.

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