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

NCERT Solutions for Class 8 Maths Chapter 15 Introduction to Graphs Ex 15.3 are the part of NCERT Solutions for Class 8 Maths. Here you can find the NCERT Solutions for Class 8 Maths Chapter 15 Introduction to Graphs Ex 15.3.

Ex 15.3 Class 8 Maths Question 1.

Draw the graphs for the following tables of values, with suitable scales on the axes.
(a) Cost of apples

Number of apples	1	2	3	4	5
Cost (in ₹)	5	10	15	20	25

(b) Distance travelled by a car

Time (in hours)	6 a.m.	7 a.m.	8 a.m.	9 a.m.
Distances (in km)	40	80	120	160

(i) How much distance did the car cover 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 it’s start?
(c) Interest on deposits for a year.

Deposit (in ₹)	1000	2000	3000	4000	5000
Simple Interest (in ₹)	80	160	240	320	400

(i) Does the graph pass through the origin?
(ii) Use the graph to find the interest on ₹ 2500 for a year.
(iii) To get an interest of ₹ 280 per year, how much money should be deposited?

Solution:
(a) To draw a graph of given data, we represent ‘Number of apples’ on the x-axis and ‘Cost (in ₹)’ on the y-axis. The ordered pairs (1, 5), (2, 10), (3, 15), (4, 20) and (5, 25) are plotted as points and are joined by the line segments as shown in the figure. This gives the required graph.

(b) To draw time-distance graph, we represent the ‘Time (in hours)’ on the x-axis and the ‘Distances (in km)’ on the y-axis.
Scale: 2 units = 1 hour on x-axis and 1 unit = 10 km on y-axis.
Plot the points (6, 40), (7, 80), (8, 120) and (9, 160).
Join them by the line segments to get the required graph as shown below:

(i) We observe from the graph that the distance covered by the car during 7.30 a.m. to 8.00 a.m. is 20 km. (∵ 120 – 100 = 20 km)
(ii) The time when the car had covered 100 km since it’s start is 7.30 a.m.
(c) To draw principal-simple interest graph, we represent ‘deposits (in ₹)’ on the x-axis and the ‘simple interest (in ₹)’ on the y-axis.
Scale: 1 unit = ₹ 1000 on x-axis.
1 unit = ₹ 80 on y-axis.
Plot the points (1000, 80), (2000, 160), (3000, 240), (4000, 320) and (5000, 400).

Join these points to get the required graph.
(i) Yes, the graph passes through the origin.
(ii) Corresponding to the principal ₹ 2500 on the x-axis, we get the interest to be ₹ 200 on the y-axis.
(iii) Corresponding to the interest ₹ 280 per year on the y-axis, we get the principal to be ₹ 3500 on the x-axis.

Ex 15.3 Class 8 Maths Question 2.

Draw a graph for the following.
(i)

Side of square (in cm)	2	3	3.5	5	6
Perimeter (in cm)	8	12	14	20	24

Is it a linear graph?
(ii)

Side of square (in cm)	2	3	4	5	6
Area (in cm²)	4	9	16	25	36

Is it a linear graph?

Solution:
(i) To draw the graph of the given data, we represent the ‘side of square (in cm)’ on the x-axis and the ‘perimeter (in cm)’ on the y-axis. Scale: 1 unit = 1 cm on x-axis and y-axis.
Plot the points (2, 8), (3, 12), (3.5, 14), (5, 20) and (6, 24). Join these points to get the required graph.

Yes, it is a linear graph.

(ii) To draw the graph of the given data, we represent the ‘side of square (in cm)’ on the x-axis and the ‘area (in cm²)’ on the y-axis. Scale: 1 unit = 1 cm on x-axis and 1 unit = 1 cm² on y-axis.
Plot the points (2, 4), (3, 9), (4, 16), (5, 25) and (6, 36). Join these points to get the required graph.