Punjab State Board PSEB 7th Class Maths Book Solutions Chapter 1 Integers Ex 1.3 Textbook Exercise Questions and Answers.

## PSEB Solutions for Class 7 Maths Chapter 1 Integers Ex 1.3

1. Find the product of :

(i) (-15) × 0

(ii) (-35) × 1

(iii) (-13) × (-12)

(iv) (-20) × 16

(v) (-15) × (-4) × (-5)

(vi) (-8) × (-5) × 9

(vii) (-2) × (-5) × (-4) × (-10)

(viii) (-8) × 0 + [(-5) × (-4)]

Answer:

(i) (-15) × 0 = 0.

(ii) (-35) × 1 = -35.

(iii) (-13) × (-12) = 156.

(iv) (-20) × 16 = -(20 × 16) = -320

(v) (-15) × (-4) × (-5) = (-15 × -4) × (-5)

= 60 × (-5)

= -(60 × 5)

= -300.

(vi) (-8) × (-5) × 9

= [(-8) × (-5)] × 9

= 40 × 9 = 360.

(vii) (-2) × (-5) × (-4) × (-10)

= [(-2) × (-5)] × [(-4) × (-10)]

= 10 × 40 = 400.

(viii) (-8) × 0 + [(-5) × (-4)]

= [(-8) × 0] + [(-5) × (-4)]

= 0 + 20 = 20.

2.

Question (i).

Verify : 15 × [9 + (-6)] = (15 × 9) + (15 × (-6)]

Answer:

L.H.S. = 15 × [9 + (-6)]

= 15 × [9 – 6]

= 15 × 3 = 45.

R.H.S. = (15 × 9) + [(15 × (-6)]

= 135 + (-90)

= 135 – 90 = 45

∴ L.H.S = R.H.S.

Question (ii).

Verify : 18 × [(-5) + (-4)] = [18 × (-5)] + [18 × (-4)]

Answer:

L.H.S. = 18 × [(-5) + (-4)]

= 18 × (-9)

= -162.

R.H.S. = [(18) × (-5)] + [18 × (-4)] = (-90) + (-72)

= – 162.

∴ L.H.S. = R.H.S.

3. Fill in the blanks :

Answer:

(i) 15 × 0 = 0.

(ii) -25 × -1 = 25.

(iii) (-15) × 18 = 18 × (-15)

(iv) (-10) × [(-15) + (-5)] = (-10) × -15 + (-10) × (-5)

(v) (-6) × [(-5) × (-18)] = (-6) × -5 × -18.

4. Find product using properties :

Question (i).

15 × (-20) + (-20) × (-5)

Answer:

15 × (-20) + (-20) × (-5)

= (-20) × [15 + (-5)]

= (-20) × [15 – 5]

= (-20) × (10)

= -200.

Question (ii).

(15 × 8) × 50

Answer:

(15 × 8) × 50

= 120 × 50

= 6000.

Question (iii).

8 × (40 – 5)

Answer:

8 × (40 – 5)

= 8 × 40 – 8 × 5

= 320 – 40

= 280.

Question (iv).

510 × (-45) + (-510) × 55

Answer:

510 × (-45) + (-510) × 55

= 510 [(-45) + (-55)]

= 510 [-100]

= -51000.

5. In a class test containing 15 questions, 2 marks are awarded for every correct answer and (-1) mark awarded for every incorrect answer and 0 mark for questions not attempted.

(i) Kritika gets 5 correct and 10 incorrect answers. What is her score ?

(ii) Rohan gets 7 correct and 7 incorrect answers out of 14 questions he attempted. What is his score ?

Answer:

(i) Marks given for one correct answer = 2

Marks given for 5 correct answers = 2 × 5 = 10

Marks given for one incorrect answer = -1

Marks given for 10 incorrect answers = -1 × 10 = -10

Total marks Kritika scored in the test = 10 + (-10)

= 10 – 10 = 0.

(ii) Marks given for one correct answer = 2

Marks given for 7 correct answers = 2 × 7 = 14

Marks given for one incorrect answer = -1

Marks given for 7 incorrect answers = – 1 × 7 = -7

Total marks Rohan scored in the test = 14 + (-7)

= 14 – 7 = 7.

6. Multiple Choice Questions :

Question (i).

(-19) – (13) is equal to

(a) -32

(b) 6

(c) -6

(d) None of these.

Answer:

(c) -6

Question (ii).

(-6) × (-5) × 0 is equal to :

(a) 0

(b) -6

(c) -5

(d) 30.

Answer:

(a) 0

(iii) 0 ÷ (-10) is equal to :

(a) 0

(b) -1

(c) -10

(d) None of these.

Answer:

(a) 0

(iv) (-33) × 102 + (-33) × (-2) is equal to :

(a) 3300

(b) -3300

(c) 3432

(d) -3432.

Answer:

(b) -3300

(v) 101 × (-1) + 0 × (-1) is equal to :

(a) -101

(b) 101

(c) -102

(d) 102.

Answer:

(a) -101