Telanagana SCERT Solution Class VII (7) Math Chapter 1 Integers.
Exercise 1 Solution
(2)
(i) 17 – (-14)
= 17 + 14
= 31
(ii) 13 – (-8)
= 13 + 8
= 21
(iii) 19 – (-5)
= 19 + 5
= 24
(iv) 15 – 28/
= -13
(v)
25- 33
= – 8
(vi) 80 – (-50)
= 80 + 50
= 130
(vii) 150 – 75
= 75
(viii) 32 – (-18)
= 32 + 18
= 50
Exercise 3
(1)
(i) (-100) x (-6) = 600
(ii) (-3) x (-1) = 3
(iii) 100 x (-6) = -600
(iv) (-20) x (-10) = 200
(v) 15 x (-3) = -45
(2)
(i) 3 x (-1)
= -3
(ii) (-1) x 225
= -225
(iii) (-21) x (-30)
= 630
(iv) (-316) x (-1)
= 316
(v) (-15) x 0 x (-18)
= 0
(vi) (-12) x (-11) x (10)
= -12 x (-110)
= 1320
(vii) 9 x (-2) x (-6)
= 9 x 18
(viii) (-18) x (-5) x (-4)
= – 18 x 20
= – 360
(ix) (-1) x (-2) x (-3) x 4
= (-1) x (-2) x (-12)
= (-1) x (24)
= – 24
(x) (-3) x (-6) x (-2) x (-1)
= (-3) x (-6) x 3
= (-3) x (-18)
= 54
(3) Required forcing process temperature at 400c.
∴ The rote at every hour = 50c
∴ The rote at 10 hour = (5×10)0c = 500c
Therefore, after 10 hours after the process begins = 400 – 500
= 100c
(4)
(i) Gopi gets 5 correct = 5 x 3
= 15 marks
And Gopi gets 5 incorrect = 5 x (-1)
= -5 marks
∴ Gopi scared = (15 + (-5)
= 15 – 5
= 10
(ii) Reshma gets 7 correct = 7 x 3
=21 marks
3 incorrect = 3 x (-1)
= -3 marks
∴ Reshma’s score = 21 + (-3)
= 21 – 3
=18
(iii) Reshmi get 3 correct = 3 x 3
= 9 marks
4 incorrect = 4 x (-1) marks
∴ Reshmi scored = 9 + (-4)
= 9 – 4
= 5
(5)
(i) 3000 bags of basmati rice = 3000 x 10 Rs.
5000 bags of non- basmati rice = 5000 x 5 Rs.
∴ Net profit = (30000 – 25000)
= 5000
(ii) Let x be the number of bags of basmati rice.
∴ 10x = 6400 x 5
X = 6400 x 5/10
X = 3200
(6)
(i) (-3) x (-9) = 27
(ii) 5 x (-7) = -35
(iii) 7 x (-8) = -56
(iv) (-11) x (-12) = 132
Exercise 5
(1)
(i) L.H.S. = 18 x [7 + (-3)]
= 18 x (+4)
= 72
R.H.S. = [18 x 7] + [18 x (-3)]
= 126 + (-54)
= 72
∴ L.H.S. = R.H.S. (Proved)
(ii) L.H.S. = (-21) x [(-4) + (-6)]
= -21 x (-10)
= 210
R.H.S. = [(-21) x (-4)] + [(-21) x (-6)]
= 24 + 126
= 210
∴ L.H.S. = R.H.S. (Proved)
(2)
(i) (-1) x a = -a
(ii) (-1) x (-5)
= 5
(3)
(i) 26 x (-48) + (-48) x (-36)
= (-48) x [26 + (-36)]
= -48 x – 10
= 480
(ii) 8 x 53 x (-125)
= 424 x – 125
= -53000
(iii) 15 x (-25) x (-4) x (-10)
= 15 x (-25) x 40
= 15 x (-1000)
= -15,000
(iv) (-41) x 102
= -4182
(v) 625 x (-35) + (-625) x 65)
= -625 x (35 + 65)
= -625 x 100
= -62500
(vi) 7 x (50-2)
= (7 x 50) – (7 x 2)
= 350 – 14
= 336
(vii) (-17) x (-29)
= 493
(viii) (-57) x (-19) + 57
= -57 x [-19 + (-1)]
= -57 x (-220)
= 1140
Exercise – 6
(1)
(i) (-25) ÷ (-1) = 25
(ii) (-49) ÷ 1 = -49
(iii) 50 ÷ 0 = not difined
(iv) 0 ÷ 1 = 0
Exercise – 7
(1)
(i) Bharati get correct answer = 9
Incorrect answer = 15 – 9
= 6
∴Her scored = (9 x 4) + [6 x (-2)]
= 36 + (-12)
= 36 – 12
= 24
(ii) Hema attempts 5 questions she scored = 5 x 4
=20
(2)
(i) The company profit on 7000 bags of white connect = 9 x 7000 Rs
= 63,000 Rs.
The company loss on 6000 bags of grey cement = 5 x 6000
= 30,000
∴ Net profit = (63000-30000)
= 33,000
(ii) Let, the number of white cement bags be = X
∴ 9x = 5400 x 5
X = 5400 / 9 x 5
X = 600 x 5
= 3000
(3) Temperature at 12 noon = 100c above zero
= 100c
Decrease at 20c/hour.
Final temperature = 80c below zero
= -80c
Change in temperature = 10 – (-8)
= 10 + 8
= 180c
Rate of decrease = 18/hour
Time = 18/2
= 9 hours
So, the temperature is 80c below zero at 9 p.m.
The temperature at midnight = 12 am
Time = 10 – 2 x (12)
= 10 – 24
= -14
Thus, the temperature at midnight is 140c below zero.
(4)
(i) Radhika scored = 20marks
She get correct answers = 12 x 3
= 36
Let, Radhika attempt incorrect answer be x
∴ -2x = 20 – 36
X = -16/-2
= 8
Thus, the number of incorrect answer is 8
(ii) Mohini scored = -5 marks
She get correct answer = 7 x 3
= 21 marks
Let, Mohini attempt incorrect answer be X
∴ -2x = -5 -21
x = -26/-2
= 13
Thus, the number of incorrect answer is 13
(5) The elevator has to travel 10m till the ground, then 350m more.
So, the total distance to travel is (350 + 10) m
= 360m
Rate of elevator’s speed = 6m/minute
∴ Time = distance/speed
= 360/6
= 60 minutes
= 1 hour