S.chand publication New Learning Composite mathematics solution of class 8 Chapter 15 Line Graphs Exercise 15B

 Exercise 15B

Question 1

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Question 2

(a) y = x + 5

X	0	4	7	*
y	5	9	12	*

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(b) y = 2x

X	1	3	6
y	2	6	12

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(c) y = 2x – 3

X	0	3	4	5
y	-3	3	5	7

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(d) y = x – 5

X	5	8	9	11
y	0	3	4	6

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Question 3

(a) Y = 5X

X	1	2	3
y	5	10	15

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(b) 

(i) X = 5

∴ Y = 5X =5 x 5 = 25

∴ Locate by going 5 positive units along the X axis & 25 positive units along the Y axis.

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(ii) X = 6

∴ Y = 5X = 5 x 6 = 30

∴ Locate by going 6 positive units along the X axis & positive units along the Y axis.

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Question 4

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x	1	2	3	4	5	6	7	8
y	1.6	3.2	4.8	6.4	8	9.6	11.2	12.8

Here x is represents to mile.

Y is represents to km.

(a) 1 miles = 1.6 km

4.5 miles = (1.6 x 4.5) km

= 7.2 km

(b) 1.6 km = 1 miles

1 km = 1/ 1.6 miles

8 km = 1/ 1.6 x 8 miles

= 5 miles.

Question 5

(b) Approximately 9.20 am

* Increasing

(c) 2 hours

(d) At 4 pm temperature will be -> 38.5℃

At 4 pm temperature will be -> 35℃

Temperature fall = 38.5 – 35.0

= 3.5℃

Question 6

Question 7

(a) 2 cars

(b) (15 + 8 +10) = 33 cars are sold

(c) Sep & Oct

Question 8

(a)

(i) Smiliti’s temperature at p.m. Saturday was 38.8oc

(ii) Smiti’s temperature at 8 am Sunady was 38.6o c

(iii) Smiti’s temperature at midnight Sunday 37.8o c

(iv) Smiti’s temperature at 12 h after midnight Sunday was 37.2oc

(b) The change in her temperature from 4 pm on Sunday to 4 am on Monday down 0 – 2o c

(c) Around noon Sunday, because of the sharp decrease in her temperature.

Question 9

(a)

(i) Y -> 2500 (deposit)

X -> 160 + 240 / 2

= 400/2

= 200

S.I. = 200

(b) Yes, It is linear graph

Question 10

(a) r = 42

C = 2πr

= 2 x 22/7 x 42

= 264

r	7	14	21	28	35	42
c	44	88	132	176	220	264

(b) When,

C = 220 unit

∴ R = 35 Unit