Class 9 Maths Ganita Manjari Chapter 3 Exercise 3.2 Solutions: The World of Numbers
Integers become easier to understand when positive and negative numbers are connected with real situations. Class 9 Maths Ganita Manjari Chapter 3 Exercise 3.2 Solutions focus on temperature change, profit-loss, debt, fortune and integer operations Class 9. This exercise from The World of Numbers helps students see why negative numbers are needed beyond natural numbers.
In Ganita Manjari Class 9 Chapter 3 Exercise 3.2, students use integers Class 9 concepts to solve questions based on Ladakh temperature, a spice trader’s loan and profit, and debt and fortune integers. These Class 9 Maths Chapter 3 Exercise 3.2 Solutions also explain Brahmagupta rules for zero and integers through simple examples such as subtracting a negative number, multiplying negative numbers and dividing integers.
NCERT Solutions for Class 9 Maths Chapter 3 Exercise Set 3.2
Class 9 Maths Ganita Manjari Chapter 3 Exercise 3.2 Solutions
Question 1. The temperature in the high-altitude desert of Ladakh is recorded as 4°C at noon. By midnight, it drops by 15°C. What is the midnight temperature?
Answer:
Temperature at noon = 4°C
Drop in temperature = 15°C
Midnight temperature = 4 - 15
= -11°C
Final answer:
The midnight temperature is -11°C.
Question 2. A spice trader takes a loan of ₹850. The next day, he makes a profit of ₹1,200. The following week, he incurs a loss of ₹450. Write this sequence as an equation using integers and calculate his final financial standing.
Answer:
Loan of ₹850 = -850
Profit of ₹1,200 = +1200
Loss of ₹450 = -450
Final standing:
-850 + 1200 - 450
= 350 - 450
= -100
Final answer:
Equation: -850 + 1200 - 450 = -100. The trader has a debt of ₹100.
Question 3. Calculate the following using Brahmagupta’s laws.
(i) (-12) × 5
Answer:
A debt multiplied by a fortune gives a debt.
(-12) × 5 = -60
Final answer:
-60
(ii) (-8) × (-7)
Answer:
A debt multiplied by a debt gives a fortune.
(-8) × (-7) = 56
Final answer:
56
(iii) 0 - (-14)
Answer:
Subtracting a negative number is the same as adding the corresponding positive number.
0 - (-14) = 0 + 14
= 14
Final answer:
14
(iv) (-20) ÷ 4
Answer:
A negative number divided by a positive number gives a negative number.
(-20) ÷ 4 = -5
Final answer:
-5
Question 4. Explain, using a real-world example of debt, why subtracting a negative number is the same as adding a positive number.
Answer:
A negative number can represent debt.
Suppose a person has ₹10. If a debt of ₹5 is removed, the person becomes ₹5 richer.
Mathematically:
10 - (-5) = 10 + 5
= 15
Final answer:
Subtracting a negative number means removing a debt, which increases the value. Therefore, 10 - (-5) = 15.
Related Links – Class 9 Maths Chapter 3