The World of Numbers | Exercise 3.2

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?

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Solution

We need to find the final temperature after a drop.

Step 1 — Identify Given Information

Let's note the initial temperature. The temperature at noon is 4 °C. The temperature drops by 15 °C.

Diagram 1

Step 2 — Calculate Midnight Temperature

We will subtract the temperature drop from the initial temperature. This gives us the midnight temperature.

Midnight temperature=Initial temperature−Temperature drop\text{Midnight temperature} = \text{Initial temperature} - \text{Temperature drop}

=4−15= 4 - 15

−11 °C\boxed{-11 \text{ °C}}

Answer

(i) The midnight temperature is -11 °C.

More questions in Exercise 3.2

Q1

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?

Q2

A spice trader takes a loan (debt) of ₹850. The next day, he makes a profit (fortune) 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.

Q3

Calculate the following using Brahmagupta's laws:

(i) (−12)×5(-12) \times 5

(ii) (−8)×(−7)(-8) \times (-7)

(iii) 0−(−14)0 - (-14)

(iv) (−20)÷4(-20) \div 4

Q4

Explain, using a real-world example of debt, why subtracting a negative number is the same as adding a positive number (e.g., 10−(−5)=1510 - (-5) = 15).

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