Table of Contents

Toggle## Class 7, Maths, Chapter 1, Exercise 1.3 Solutions

**Q.1. Find each of the following products:**

**(a) 3 × (–1) **

**(b) (–1) × 225**

**(c) (–21) × (–30) **

**(d) (–316) × (–1)**

**(e) (–15) × 0 × (–18) **

**(f) (–12) × (–11) × (10)**

**(g) 9 × (–3) × (– 6) **

**(h) (–18) × (–5) × (– 4)**

**(i) (–1) × (–2) × (–3) × 4 **

**(j) (–3) × (–6) × (–2) × (–1)**

**Q.2. Verify the following:**

**(a) 18 × [7 + (–3)] = [18 × 7] + [18 × (–3)]**

**(b) (–21) × [(– 4) + (– 6)] = [(–21) × (– 4)] + [(–21) × (– 6)]**

**Q.3. (i) For any integer a, what is (–1) × a equal to?**

**(ii) Determine the integer whose product with (–1) is**

**(a) –22 **

**(b) 37 **

**(c) 0**

**Q.4. Starting from (–1) x 5, write various products showing some pattern to show (–1) × (–1) = 1.**

**Ans: **The various products are,

= (-1) x 5 = – 5

= (-1) X 4 = – 4

= (-1) x 3 = – 3

= (-1) x 2 = – 2

= (-1) x 1= – 1

= (-1) x 0 = 0

= (-1) x (-1) = 1

We can conclude that:

(i) The product of one negative integer and one positive integer is negative integer.

(ii) The product of two negative integers is a positive integer.

**Q.5. Find the product, using suitable properties:**

**(a) 26 × (– 48) + (– 48) × (–36) **

**(b) 8 × 53 × (–125)**

**(c) 15 × (–25) × (– 4) × (–10) **

**(d) (– 41) × 102**

**(e) 625 × (–35) + (– 625) × 65 **

**(f) 7 × (50 – 2)**

**(g) (–17) × (–29) **

**(h) (–57) × (–19) + 57**

**Q.6. A certain freezing process requires that room temperature be lowered from 40°C at the rate of 5°C every hour. What will be the room temperature 10 hours after the process begins?**

**Q.7. In a class test containing 10 questions, 5 marks are obtained for every correct answer and (–2) marks are obtained for every incorrect answer and 0 for questions not attempted.**

**(i) Mohan gets four correct and six incorrect answers. What is his score?**

**(ii) Reshma gets five correct answers and five incorrect answers, what is her score?**

**(iii) Heena gets two correct and five incorrect answers out of seven questions she attempts. What is her score?**

**Q.8. A cement company earns a profit of ****₹ ****8 per bag of white cement sold and a loss of ****₹**** 5 per bag of grey cement sold.**

**(a) The company sells 3,000 bags of white cement and 5,000 bags of grey cement in a month. What is its profit or loss?**

**(b) What is the number of white cement bags it must sell to have neither profit nor loss, if the number of grey bags sold is 6,400 bags.**

**Ans:**

**Q.9. Replace the blank with an integer to make it a true statement.**

**(a) (-3) x _______ = 27**

**(b) 5 x ___________= -35**

**(c) ____________ x (-8) = -56**

**(d) ___________ x (-12) = 132**