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The Junk Seller - The Junk Seller

Grade 4CBSE

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

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Introduction to money: Counting different denominations of notes and coins (Rs 2000, Rs 500, Rs 100, Rs 50, Rs 20, Rs 10, Rs 5, Rs 2, and Rs 1).

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Mental Math for multiplication: Breaking down numbers to multiply quickly, for example, 12×6=(10×6)+(2×6)=60+12=7212 \times 6 = (10 \times 6) + (2 \times 6) = 60 + 12 = 72.

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Calculating 'Cost Price' (CP): The amount of money paid to buy an item.

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Calculating 'Selling Price' (SP): The amount of money received by selling an item.

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Concept of Profit: When the Selling Price is greater than the Cost Price (SP>CPSP > CP), the difference is called Profit.

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Concept of Loss: When the Selling Price is less than the Cost Price (SP<CPSP < CP), the difference is called Loss.

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Unitary Method: Finding the price of a single unit and then multiplying it by the required quantity to find the total cost.

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Calculating interest: Understanding that borrowing money from a bank or a person requires paying back a small extra amount called interest.

📐Formulae

Total Price=Price of 1 unit×Total number of unitsTotal\ Price = Price\ of\ 1\ unit \times Total\ number\ of\ units

Profit=Selling Price−Cost PriceProfit = Selling\ Price - Cost\ Price

Loss=Cost Price−Selling PriceLoss = Cost\ Price - Selling\ Price

Total Money Back=Borrowed Amount+InterestTotal\ Money\ Back = Borrowed\ Amount + Interest

💡Examples

Problem 1:

Kiran bought 1 kg of iron for Rs 14 and sold it for Rs 16. How much money will she earn if she sells 32 kg of iron?

Solution:

Profit on 1 kg = Rs 16−14=216 - 14 = 2. Total profit on 32 kg = 32×2=6432 \times 2 = 64.

Explanation:

First, find the profit on one unit by subtracting the cost price from the selling price. Then, multiply that profit by the total weight sold.

Problem 2:

Dinu paid Rs 800 for some junk. He sold it for Rs 950. Calculate the profit.

Solution:

950−800150\begin{array}{r} 950 \\ - 800 \\ \hline 150 \end{array} Profit = Rs 150.

Explanation:

Since the selling price is higher than the cost price, we subtract the cost price (Rs 800) from the selling price (Rs 950) to find the profit.

Problem 3:

Calculate the total money for the following: 5 notes of Rs 100, 3 notes of Rs 50, and 10 notes of Rs 10.

Solution:

5 notes of Rs 100 = 5×100=5005 \times 100 = 500. 3 notes of Rs 50 = 3×50=1503 \times 50 = 150. 10 notes of Rs 10 = 10×10=10010 \times 10 = 100. Total = 500+150+100=750500 + 150 + 100 = 750.

Explanation:

Multiply the value of each note by the number of notes and then add all the totals together.

Problem 4:

Hari took a loan of Rs 300 from a bank. He pays back Rs 54 every month for 6 months. How much total money does he pay back?

Solution:

Monthly payment = Rs 54. Total payment = 54×6=32454 \times 6 = 324.

Explanation:

Multiply the monthly installment (Rs 54) by the number of months (6) to find the total amount returned to the bank.