GANITA PRAKASH · GRADE 8 · PART II · CHAPTER 1
TRADE — Cost, selling price, discount and tax
Think first. Use AI purposefully. Verify always.
DISCOVER
Begin with a prediction.
A ₹1800 marked price is discounted by 35%. If the cost was ₹900, can the seller still make a profit?
Sketch or write an independent attempt before reading on. Test your idea using the model.
Understand
CP is cost price, MP is marked price, and SP is selling price. Discount uses MP as base; trading profit or loss percentage uses CP. A stated tax rate applies to its specified taxable amount.
Key Ideas
Discount is not automatically a loss. Gross profit excludes other expenses; net profit includes them. Always name the margin denominator.
Visualise
Cost → marked price → selling price
Predict first. Change the controls, then compare your reasoning.
₹100→MP
₹150→SP
₹75
Loss on cost: 25%. Markup uses ₹100; discount uses ₹150.
A discount uses the marked price
Predict first. Change the controls, then compare your reasoning.
On a marked price of ₹1800, discount = ₹450; selling price = ₹1,350. Discount base: ₹1800.
Tax on the stated amount
Predict first. Change the controls, then compare your reasoning.
₹8250+Tax
₹1,485
Total = ₹9,735. Tax base is ₹8250. These are given educational rates, not advice about current tax rates.
Method
Follow the price journey in order. Identify the base at each arrow. Subtract other expenses to move from gross profit to net profit; a net-profit-on-revenue margin uses revenue, not CP.
Worked Example
Given
CP ₹900, MP ₹1800, discount 35%.
To Find
Selling price and profit percentage on cost
Reasoning
SP = MP × (1 − discount rate); profit percentage uses CP.
Solution
- SP = 1800 × 0.65 = ₹1170.
- Profit = 1170 − 900 = ₹270.
- × 100 = 30%.
Result
SP is ₹1170; profit on cost is 30%.
AIMS Method
- A — Attempt independently
Estimate and predict first. - I — Investigate the idea
Identify the whole and the percentage base. - M — Make connections
Connect fractions, decimals, bars and multipliers. - S — Scrutinise your reasoning
Check units, bases and the reasonableness of the result.
Think first. Use AI purposefully. Verify always.
Focused Practice
Revenue is ₹150000, goods cost ₹100000 and other expenses ₹5000. Find gross profit, net profit and net-profit-on-revenue percentage.
Check & Feedback
Name the whole, explain the method and give one check that would catch a wrong percentage base.
Textbook connection: Ganita Prakash · Grade 8 · Part II · Fractions in Disguise · printed page 17