A man sells potatoes at ₹27 per kg, which he bought at ₹25 per kg. He also uses a faulty weight and each time gives 800 g instead of 1 kg. His actual gain percentage is:
- AOption (a)
35%
- BOption (b)
20%
- COption (c)
25%
- DOption (d)
40%
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Correct answer
35%
Why this answer is correct
Shortcut Trick
Use the Successive Multiplication method for price change and weight fraud.
Price Ratio (CP : SP) = 25 : 27.
Weight Ratio (Quantity given : Quantity charged) = 800 : 1000 = 4 : 5.
Effective Ratio = (25 × 4) : (27 × 5) = 100 : 135.
Gain% = (135 − 100) ÷ 100 × 100 = 35%.
∴ The correct answer is 35%.
Alternate Method
Given → CP per kg = ₹25, SP per kg = ₹27, True weight = 1000 g, Faulty weight = 800 g. Formulas: Gain% = (Total SP − Total CP) ÷ Total CP × 100 | Total CP = CP × (Actual weight ÷ 1000).
⇒ Cost of 1000 g = ₹25. Therefore, Actual Cost of 800 g = (25 ÷ 1000) × 800 = ₹20.
⇒ The shopkeeper sells 800 g (which cost him ₹20) for the price of 1 kg (₹27).
⇒ Selling Price obtained = ₹27.
⇒ Profit = SP − CP = 27 − 20 = ₹7.
⇒ Gain% = (7 ÷ 20) × 100 = 35%.
∴ The correct answer is 35%.
Additional Information
Dishonest Dealer Concept
When a dealer uses less weight, the Gain% = [Error ÷ (True Value − Error)] × 100 if he sells at cost price.
Effective Profit
If there is a profit on price (P%) and a profit due to weight fraud, the total profit is calculated by compounding the ratios of investment to returns.



