NCERT Class 7th Mathematics Chapter 1 – Integers Solutions Exercise 1.1 Solutions, Class 7th maths solutions, NCERT Maths solutions for class 7th, Questions and answers of NCERT class 7th Mathematics.
Please find the detailed Solutions for class 7th Maths chapter 1 exercise 1.1, you can check all the solutions from here chapter wise
NCERT Class 7th Mathematics Chapter 1 – Integer Solutions Exercise 1.1 Solutions
Exercise 1.1
1. Following number line shows the temperature in degree Celsius (0C) at different places on a particular day.
(a) Observe this number line and write the temperature of the places marked on it.
Ans. Lahulspiti : -80C, Srinagar: -20C, Shimla: 50C, Ooty:140C, Bengaluru: 220C
(b) What is the temperature difference between the hottest and the coldest places among the above?
Ans. Temperature of hottest place (Bengaluru) = 220C
Temperature of coldest place (Lahulspiti) = -80C
Temperature difference between them = 220C- (-80C) = 300C
(c) What is the temperature difference between Lahulspiti and Srinagar?
Ans. Temperature of Lahulspiti = -80C
Temperature of Srinagar = -20C
Temperature difference between them = -20C -(-80C) = -20C + 80C = 60C
(d) Can we say temperature of Srinagar and Shimla taken together is less than the temperature at Shimla? Is it also less then the temperature at Srinagar?
Ans. Temperature of Shimla = 50C
Temperature of Srinagar = -20C
Temperature of them together = 50C + (-20C) = 50C-20C = 30C
Therefore the temperature of Srinagar and Shimla together is less than temperature of Shimla and it is not less than the temperature of Srinagar.
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?
Ans. Jack’s s total score at the end = 25 + (-5) + (-10) + 15 + 10 = 35
3. At Srinagar temperature was -50C on Monday and then it dropped by 20C on Tuesday. What was the temperature of Srinagar on Tuesday? On Wednesday, it rose by 40C. What was the temperature on this day?
Ans. Temperature of Srinagar on Tuesday = -50C -20C = -70C
Temperature of Srinagar on Wednesday = -70C + 40C = -30C
4. A plane is flying at the height of 5000m above the sea level. At a particular point, it is exactly above a submarine floating 1200m below the sea level. What is the vertical distance between them?
Ans. Height of plane above sea level = 5000 m
Depth of submarine below sea level = 1200 m
Vertical distance between plane and submarine = 5000 m + 1200 m = 6200 m
5.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.
Ans. Amount deposited by Mohan will be represented by a positive integer = Rs 2,000
Amount withdrawal by him on next day = Rs 1,642
Balance in Mohan’s account after the withdrawal = Rs 2000 – Rs 1642 = Rs 358
6. 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?
Ans. Distance travelled by Rita towards east = 20 km
Distance travelled towards west will be represented by a negative integer = -30 km
Her final position = 20 km – 30 km = -10 km
7. In a magic square each row, column and diagonal have the same sum. Check which of the following is a magic square.
Ans. Square (ii) is a magic square.
8. Verify a – (– b) = a + b for the following values of a and b.
(i) a = 21, b = 18 (ii) a = 118, b = 125 (iii) a = 75, b = 84 (iv) a = 28, b = 11
Ans (i). a = 21, b = 18
a – (– b) = 21 – (-18) = 21 + 18 = a + b
(ii) a = 118, b = 125
a – (– b) = 118 – (-125) = 118 + 125 = a + b
(iii) a = 75, b = 84
a – (– b) = 75 – (-84) = 75 + 84 = a + b
(iv) a = 28, b = 11
a – (– b) = 28 – (-11) = 28 + 11 = a + b
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
10. A water tank has steps inside it. A monkey is sitting on the topmost step (i.e., the first step). The water level is at the ninth step.
(i) He jumps 3 steps down and then jumps back 2 steps up. In how many jumps will he reach the water level?
Ans. 11 jumps
(ii) After drinking water, he wants to go back. For this, he jumps 4 steps up and then jumps back 2 steps down in every move. In how many jumps will he reach back the top step?
Ans. 5 jumps
(iii) If the number of steps moved down is represented by negative integers and the number of steps moved up by positive integers, represent his moves in part (i) and (ii) by completing the following; (a)– 3 + 2 – … = – 8 (b) 4 – 2 + … = 8. In (a) the sum (– 8) represents going down by eight steps. So, what will the sum 8 in (b) represent?
Ans. (a) – 3 + 2 – 3 + 2 – 3 + 2 – 3 + 2 -3 + 2 – 3 = -8
(b) 4 – 2 + 4 – 2 + 4 = 8
In (b), 8 represents going up.
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