Class 7th - Integers (CBSE)

Integers

1. 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?
2. 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 temp on this day?
3. A plane is flying at the height of 5000 m above the sea level. At a particular point, it is exactly above a submarine floating 1200 m below the sea level. What is the vertical distance between them?
4. Mohan deposits Rs 2,000 in his bank account and withdraws Rs 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.
5. Rita goes 20 km towards east from a point A to the point B. From B, she moves 30 km towards west along the same road. If the distance towards east is represented by a positive integer then, how will you represent the distance travelled towards west? By which integer will you represent her final position from A?
6. 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        
 
 
7. Suppose we represent the distance above the ground by a positive integer and that below the ground by a negative integer, then answer the following:      (i) An elevator descends into a mine shaft at the rate of 5 metre per minute. What will be its position after one hour?           (ii) If it begins to descend from 15 m above the ground, what will be its position after 45 minutes?
8. 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  
9. 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?
10. In a class test containing 10 questions, 5 marks are awarded for every correct answer and (–2) marks are awarded 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?
11. A cement company earns a profit of Rs 8 per bag of white cement sold and a loss of Rs 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.
 
12. In a test (+5) marks are given for every correct answer and (–2) marks are given for every incorrect answer.      (i) Radhika answered all the questions and scored 30 marks though she got 10 correct answers.              (ii) Jay also answered all the questions and scored (–12) marks though he got 4 correct answers. How many incorrect answers had they attempted?
 
13. A shopkeeper earns a profit of Re 1 by selling one pen and incurs a loss of 40 paise per pencil while selling pencils of her old stock.      (i) In a particular month she incurs a loss of Rs 5. In this period, she sold 45 pens. How many pencils did she sell in this period?                     (ii) In the next month she earns neither profit nor loss. If she sold 70 pens, how many pencils did she sell?
 
14. The temperature at 12 noon was 10°C above zero. If it decreases at the rate of 2°C per hour until midnight, at what time would the temperature be 8°C below zero? What would be the temperature at mid-night?
15. In a class test (+ 3) marks are given for every correct answer and (–2) marks are given for every incorrect answer and no marks for not attempting any question.             (i)Radhika scored 20 marks. If she has got 12 correct answers, how many questions has she attempted correctly?                (ii) Mohini scores –5 marks in this test, though she has got 7 correct answers. How many questions has she attempted incorrectly?             (iii) Rakesh scores 18 marks by attempting 16 questions. How many questions has he attempted correctly and how many has he attempted incorrectly?
16. An elevator descends into a mine shaft at the rate of 6 m/min. If the descent starts from 10 m above the ground level, how long will it take to reach – 350 m.