EVENTS CONVENT HIGH SCHOOL
31/07/2021 CLASS-7 SESSION2021-22(SLOT-1)
Maths
Chapter-1(EX.1.1)
INTEGERS
______________________________________
INTRODUCTION INTEGERS
Que-1 Explain
Que-2 Explain
Que-3 Explain
Que-4 Explain
Que-5 Explain
Que-8 Explain
Que-9 Explain
Question 1.Following
number line shows the temperature in degree Celsius (°C) at different places on
a particular day.
(a) Observe this number line and write
the temperature of the places marked on it.
(b) What
is the temperature difference between the hottest and the coldest places among
the above?
(c) What
is the temperature difference between Lahulspriti and Srinagar?
Cities Temperature
Lahulspriti - 8°C
Srinagar - 2°C
Shimla 5°C
(b) The temperature of the hottest place
= 22°C
The
temperature of the coldest place = -8°C
Difference
= 22°C – (-8°C)
= 22°C +
8°C = 30°C
(c)
Temperature of Lahulspriti = -8°C
Temperature
of Srinagar = -2°C
∴ Difference = -2°C –
(-8°C)
= -2°C +
8°C = 6°C
Question
2.In a quiz, positive marks are given for correct answers and negative marks
are given for incorrect answers. If Jack’s scores in five successive rounds
were 25, -5, -10, 15 and 10, what was his total at the end?
Solution:
Given
scores are 25, -5, -10, 15, 10
Marks
given for correct answers
= 25 + 15
+ 10 = 50
Marks
given for incorrect answers
= (-5) +
(-10) = -15
∴ Total marks given at the
end
= 50 +
(-15) = 50 – 15 = 35
Question
3.At Srinagar temperature was -5°C on Monday and then it dropped by 2°C on
Tuesday. What was the temperature of Srinagar on Tuesday? On Wednesday, it rose
by 4°C. What was the temperature on this day?
Solution:
Initial
temperature of Srinagar on Monday = -5°C
Temperature
on Tuesday = -5°C – 2°C = -7°C
Temperature
was increased by 4°C on Wednesday.
∴ Temperature on Wednesday
= -7°C +
4°C = -3°C
Hence,
the required temperature on Tuesday = -7°C
and the
temperature on Wednesday = -3°C
Question
4.A plane is flying at the height of 5000 m above the sea level. At a
particular point, it is exactly above a submarine flowing 1200 m below the sea
level. What is the vertical distance between them?
Solution:
Height of
the flying plane = 5000 m
Depth of
the submarine = -1200 m
∴ Distance between them
= + 5000
m – (-1200 m)
= 5000 m
+ 1200 m = 6200 m
Hence,
the vertical distance = 6200 m
Question
5.Mohan deposits ₹ 2,000 in
a bank account and withdraws ₹ 1,642
from it, the next day. If withdrawal of amount from the account is represented
by a negative integer, then how will you represent the amount deposited? Find
the balance in Mohan’s account after the withdrawal.
Solution:
The
deposited amount will be represented by a positive integer i.e., ₹ 2000.
Amount
withdrawn = ₹ 1,642
∴ Balance in the account
= ₹ 2,000 – ₹ 1,642 = ₹ 358
Hence,
the balance in Mohan’s account after the withdrawal
= ₹ 358
Question
8.Verify a – (-b) = a + b for the following values of a and 6.
(i) a =
21, b = 18
(ii) a =
118, b = 125
(iii) a =
75, b = 84
(iv) a=
28, 6 = 11
Solution:
(i) a –
(-b) = a + b
LHS = 21
– (-18) = 21 + 18 = 39
RHS = 21
+ 18 = 39
LHS = RHS
Hence, verified.
(ii) a –
(-b) = a + b
LHS = 118
– (-125) = 118 + 125 = 243
RHS = 118
+ 125 = 243
LHS = RHS
Hence, verified.
(iii) a –
(-b) = a + b
LHS = 75
– (-84) = 75 + 84 = 159
RHS = 75
+ 84 = 159
LHS = RHS
Hence, verified.
Question 9.Use the sign of >, < or = in
the box to make the statements true.
(a) (-8)
+(-4) □(-8)-(-4)
(b) (-3)
+ 7 – (19) □ 15 – 8 + (-9)
(c) 23 –
41 + 11 □ 23 – 41 – 11
(d) 39 +
(-24) – (15) □ 36 + (-52) – (-36)
(e) -231
+ 79 + 51 □ -399 + 159 + 81
Solution:
(a) (-8)
+ (-4) □ (-8) – (-4)
LHS =
(-8) + (-4) = -8 – 4 = – 12
RHS =
(-8) – (-4) = -8 + 4 = -4
Here – 12
< -4
Hence,
(-8) + (-4) [<] (-8) – (-4)
(b) (-3)
+ 7 – (19) □ 15 – 8 + (-9)
LHS =
(-3) + 7 – (19) =-3 + 7-19
= -3 – 19
+ 7
= -22 + 1
= -15
RHS = 15
– 8 + (-9)
= 15-8-9
= 15 – 17
= -2
Here -15
< -2
Hence,
(-3) + 7 – (19) [<] 15 – 8 + (-9)
(c) 23 –
41 + 11 □ 23 – 41 – 11
LHS = 23
– 41 + 11 = 23 + 11 – 41 = 34 – 41 = -7
RHS = 23
– 41 – 11 = 23 – 52 = -29 Here, -7 > -29
Hence, 23 – 41 + 11
[>] 23 – 41 – 11
INTRODUCTION INTEGERS
Que-1 Explain
Que-2 Explain
Que-3 Explain
Que-4 Explain
Que-5 Explain
Que-8 Explain
Que-9 Explain
Question 1.Following
number line shows the temperature in degree Celsius (°C) at different places on
a particular day.
(a) Observe this number line and write
the temperature of the places marked on it.
(b) What
is the temperature difference between the hottest and the coldest places among
the above?
(c) What
is the temperature difference between Lahulspriti and Srinagar?
Cities Temperature
Lahulspriti - 8°C
Srinagar - 2°C
Shimla 5°C
(b) The temperature of the hottest place
= 22°C
The
temperature of the coldest place = -8°C
Difference
= 22°C – (-8°C)
= 22°C +
8°C = 30°C
(c)
Temperature of Lahulspriti = -8°C
Temperature
of Srinagar = -2°C
∴ Difference = -2°C –
(-8°C)
= -2°C +
8°C = 6°C
Question
2.In a quiz, positive marks are given for correct answers and negative marks
are given for incorrect answers. If Jack’s scores in five successive rounds
were 25, -5, -10, 15 and 10, what was his total at the end?
Solution:
Given
scores are 25, -5, -10, 15, 10
Marks
given for correct answers
= 25 + 15
+ 10 = 50
Marks
given for incorrect answers
= (-5) +
(-10) = -15
∴ Total marks given at the
end
= 50 +
(-15) = 50 – 15 = 35
Question
3.At Srinagar temperature was -5°C on Monday and then it dropped by 2°C on
Tuesday. What was the temperature of Srinagar on Tuesday? On Wednesday, it rose
by 4°C. What was the temperature on this day?
Solution:
Initial
temperature of Srinagar on Monday = -5°C
Temperature
on Tuesday = -5°C – 2°C = -7°C
Temperature
was increased by 4°C on Wednesday.
∴ Temperature on Wednesday
= -7°C +
4°C = -3°C
Hence,
the required temperature on Tuesday = -7°C
and the
temperature on Wednesday = -3°C
Question
4.A plane is flying at the height of 5000 m above the sea level. At a
particular point, it is exactly above a submarine flowing 1200 m below the sea
level. What is the vertical distance between them?
Solution:
Height of
the flying plane = 5000 m
Depth of
the submarine = -1200 m
∴ Distance between them
= + 5000
m – (-1200 m)
= 5000 m
+ 1200 m = 6200 m
Hence,
the vertical distance = 6200 m
Question
5.Mohan deposits ₹ 2,000 in
a bank account and withdraws ₹ 1,642
from it, the next day. If withdrawal of amount from the account is represented
by a negative integer, then how will you represent the amount deposited? Find
the balance in Mohan’s account after the withdrawal.
Solution:
The
deposited amount will be represented by a positive integer i.e., ₹ 2000.
Amount
withdrawn = ₹ 1,642
∴ Balance in the account
= ₹ 2,000 – ₹ 1,642 = ₹ 358
Hence,
the balance in Mohan’s account after the withdrawal
= ₹ 358
Question
8.Verify a – (-b) = a + b for the following values of a and 6.
(i) a =
21, b = 18
(ii) a =
118, b = 125
(iii) a =
75, b = 84
(iv) a=
28, 6 = 11
Solution:
(i) a –
(-b) = a + b
LHS = 21
– (-18) = 21 + 18 = 39
RHS = 21
+ 18 = 39
LHS = RHS
Hence, verified.
(ii) a –
(-b) = a + b
LHS = 118
– (-125) = 118 + 125 = 243
RHS = 118
+ 125 = 243
LHS = RHS
Hence, verified.
(iii) a –
(-b) = a + b
LHS = 75
– (-84) = 75 + 84 = 159
RHS = 75
+ 84 = 159
LHS = RHS
Hence, verified.
Question 9.Use the sign of >, < or = in
the box to make the statements true.
(a) (-8)
+(-4) □(-8)-(-4)
(b) (-3)
+ 7 – (19) □ 15 – 8 + (-9)
(c) 23 –
41 + 11 □ 23 – 41 – 11
(d) 39 +
(-24) – (15) □ 36 + (-52) – (-36)
(e) -231
+ 79 + 51 □ -399 + 159 + 81
Solution:
(a) (-8)
+ (-4) □ (-8) – (-4)
LHS =
(-8) + (-4) = -8 – 4 = – 12
RHS =
(-8) – (-4) = -8 + 4 = -4
Here – 12
< -4
Hence,
(-8) + (-4) [<] (-8) – (-4)
(b) (-3)
+ 7 – (19) □ 15 – 8 + (-9)
LHS =
(-3) + 7 – (19) =-3 + 7-19
= -3 – 19
+ 7
= -22 + 1
= -15
RHS = 15
– 8 + (-9)
= 15-8-9
= 15 – 17
= -2
Here -15
< -2
Hence,
(-3) + 7 – (19) [<] 15 – 8 + (-9)
(c) 23 –
41 + 11 □ 23 – 41 – 11
LHS = 23
– 41 + 11 = 23 + 11 – 41 = 34 – 41 = -7
RHS = 23
– 41 – 11 = 23 – 52 = -29 Here, -7 > -29
Hence, 23 – 41 + 11
[>] 23 – 41 – 11
