Short answer English mein

$$\text{Total Cost Price} = \text{Rs. } 6000$$

Total Cost Price: $\boxed{\text{Rs. } 6000}$

Q2. What was the total selling price?

$$\text{Total Selling Price} = \text{Rs. } 7800$$

Total Selling Price: $\boxed{\text{Rs. } 7800}$

Q3. How many kg became rotten? What was the loss on them?

$$\text{Rotten Mangoes} = 150 \text{ kg} - 120 \text{ kg}$$ $$\text{Rotten Mangoes} = 30 \text{ kg}$$

$$\text{Loss} = 30 \text{ kg} \times \text{Rs. } 40/\text{kg}$$ $$\text{Loss} = \text{Rs. } 1200$$

Rotten quantity: $\boxed{30 \text{ kg}}$
Loss on them: $\boxed{\text{Rs. } 1200}$

Q4. Did the seller make a net profit or loss? How much?

$$\text{Net Profit/Loss} = \text{Total Selling Price} - \text{Total Cost Price}$$ $$\text{Net Profit/Loss} = \text{Rs. } 7800 - \text{Rs. } 6000$$

$$\text{Net Profit/Loss} = \text{Rs. } 1800$$

Since the result is positive, the seller made a profit.
Seller made a: $\boxed{\text{Net Profit}}$
How much: $\boxed{\text{Rs. } 1800}$

Section B: Case Study 3 – Water Tank

Q1. How much water was used in total?

$$\text{Total Water Used} = 1300 \text{ litres}$$

Total water used: $\boxed{1300 \text{ litres}}$

Q2. How much water is left in the tank?

$$\text{Water Left} = 1150 \text{ litres}$$

Water left in the tank: $\boxed{1150 \text{ litres}}$

Q3. If a 5th family needs 200 litres, is there enough water? Explain.

Since the water left in the tank (1150 litres) is more than the 5th family's requirement (200 litres), there is enough water.
Is there enough water: $\boxed{\text{Yes}}$
Explanation: There are $1150 \text{ litres}$ of water left in the tank, which is more than the $200 \text{ litres}$ needed.

Section C: Case Study 4 – Savings

Q1. How much does Meena spend monthly?

$$\text{Total Monthly Spending} = \text{Rent} + \text{Food} + \text{Travel}$$ $$\text{Total Monthly Spending} = \text{Rs. } 6500 + \text{Rs. } 3200 + \text{Rs. } 1800$$

$$\text{Total Monthly Spending} = \text{Rs. } 11500$$

Meena's monthly spending: $\boxed{\text{Rs. } 11500}$

Q2. How much does she save monthly?

$$\text{Monthly Savings} = \text{Monthly Income} - \text{Total Monthly Spending}$$ $$\text{Monthly Savings} = \text{Rs. } 15000 - \text{Rs. } 11500$$

$$\text{Monthly Savings} = \text{Rs. } 3500$$

Meena's monthly savings: $\boxed{\text{Rs. } 3500}$

Q3. How much will she save in 6 months?

$$\text{Savings in 6 Months} = \text{Monthly Savings} \times 6$$ $$\text{Savings in 6 Months} = \text{Rs. } 3500 \times 6$$

$$\text{Savings in 6 Months} = \text{Rs. } 21000$$

Savings in 6 months: $\boxed{\text{Rs. } 21000}$

Q4. If she wants to buy a phone for Rs 12,000, after how many months can she afford it?

$$\text{Months Required} = \frac{\text{Cost of Phone}}{\text{Monthly Savings}}$$ $$\text{Months Required} = \frac{\text{Rs. } 12000}{\text{Rs. } 3500}$$

$$\text{Months Required} \approx 3.428$$

Since the number of months must be a whole number, she will need 4 months to afford the phone.
Months to afford it: $\boxed{4 \text{ months}}$