The following graph shows the temperature of a patient in a hospital, recorded every hour.
(a) What was the patient's temperature at 1 p.m.?
(b) When was the patient's temperature 38.5°C?
(c) The patient's temperature was the same two times during the period given. What were these two times?
(d) What was the temperature at 1.30 p.m? How did you arrive at your answer?
(e) During which periods did the patient's temperature show an upward trend?
Answer :
(a) At 1 p.m., the patient's temperature was 36.5°C.
(b) The patient's temperature was 38.5°C at 12 noon.
(c) The patient's temperature was same at 1 p.m. and 2 p.m.
(d) The graph between the times 1 p.m. and 2 p.m. is parallel to the xaxis. The temperature at 1 p.m. and 2 p.m. is 36.5°C. So, the temperature at 1:30 p.m. is 36.5°C.
(e) During the following periods, the patient's temperature showed an upward trend.
9 a.m. to 10 a.m., 10 a.m. to 11 a.m., 2 p.m. to 3 p.m.
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The following line graph shows the yearly sales figure 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 the sales in 2002 and 2006.
(d) In which year was there the greatest difference between the sales as compared to its previous year?
Answer :
(a)
(i) In 2002, the sales were Rs 4 crores.
(ii) In 2006, the sales were Rs 8 crores.
(b)
(i) In 2003, the sales were Rs 7 crores.
(ii) In 2005, the sales were Rs 10 crores.
(c)
(i) In 2002, the sales were Rs 4 crores and in 2006, the sales were Rs 8 crores.
Difference between the sales in 2002 and 2006
= Rs (8  4) crores = Rs 4 crores
(d) Difference between the sales of the year 2006 and 2005
= Rs (10  8) crores = Rs 2 crores
Difference between the sales of the year 2005 and 2004
= Rs (10  6) crores = Rs 4 crores
Difference between the sales of the year 2004 and 2003
= Rs (7  6) crore = Rs 1 crore
Difference between the sales of the year 2003 and 2002
= Rs (7  4) crores = Rs 3 crores
Hence, the difference was the maximum in the year 2005 as compared to its previous year 2004.
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For an experiment in Botany, two different plants, plant A and plant B were grown under similar laboratory conditions. Their heights were measured at the end of each week for 3 weeks. The results are shown by the following graph.
(a) How high was Plant A after (i) 2 weeks (ii) 3weeks?
(b) How high was Plant B after (i) 2 weeks (ii) 3weeks?
(c) How much did Plant A grow during the 3^{rd} week?
(d) How much did Plant B grow from the end of the 2^{nd} week to the end of the 3^{rd} week?
(e) During which week did Plant A grow most?
(f) During which week did Plant B grow least?
(g) Were the two plants of the same height during any week shown here? Specify.
Answer :
The following graph shows the temperature forecast and the actual temperature for each day of a week.
(a) On which days was the forecast temperature the same as the actual temperature?
(b) What was the maximum forecast temperature during the week?
(c) What was the minimum actual temperature during the week?
(d) On which day did the actual temperature differ the most from the forecast temperature?
Answer :
Use the tables below to draw linear graphs.
(a) The number of days a hill side 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 
Number of men 
12 
12.5 
13 
13.2 
13.5 
Number of women 
11.3 
11.9 
13 
13.6 
12.8 
Answer :
A courierperson cycles from a town to a neighboring suburban area to deliver a parcel to a merchant. His distance from the town at different times is shown by the following graph.
(a) What is the scale taken for the time axis?
(b) How much time did the person take for the travel?
(c) How far is the place of the merchant from the town?
(d) Did the person stop on his way? Explain.
(e) During which period did he ride fastest?
Answer :
Can there be a time temperature graph as follows? Justify you're answer:


(i) 
(ii) 


(iii) 
(iv) 
Answer :
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)
Answer :
Draw the line passing through (2, 3) and (3, 2). Find the coordinates of the points at which this line meets the xaxis and yaxis.
Answer :
Write the coordinates of the vertices of each of these adjoining figures.
Answer :
State whether True or False. Correct those are false.
(i) A point whose x coordinate is zero and ycoordinate is nonzero will lie on the yaxis.
(ii) A point whose y coordinate is zero and xcoordinate is 5 will lie on yaxis.
(iii) The coordinates of the origin are (0, 0).
Answer :
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 Rs) 
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. 
Distance (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 its start?
(c) Interest on deposits for a year:
Answer :
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 cm^{2}) 
4 
9 
16 
25 
36 
Is it a linear graph?
Answer :
Maths  NCERT Solution  Maths : CBSE NCERT Exercise Solutions for Class 8th for Introduction to Graphs ( Exercise 15.1, 15.2, 15.3 ) will be available online in PDF book form soon. The solutions are absolutely Free. Soon you will be able to download the solutions.
Exercise 15.1 
Question 1 
Question 2 
Question 3 
Question 4 
Question 5 
Question 6 
Question 7 
Exercise 15.2 
Question 1 
Question 2 
Question 3 
Question 4 
Exercise 15.3 
Question 1 
Question 2 