Shortcut Trick
Use the Successive Multiplication Factor method:
Weight Ratio (Profit from cheating) = 1000 / 940
Price Ratio (Stated profit) = 104 / 100
Total Ratio = (1000 / 940) × (104 / 100) = 1040 / 940 = 1.10638...
Actual Profit % = (1040 − 940) / 940 × 100 = 1000 / 94 = 10.638...
∴ The correct answer is 10.64%.
Alternate Method
Given:
Actual weight = 1 kg = 1000 gm
False weight used = 940 gm
Stated profit % = 4%
Calculations:
⇒ Let the cost price (CP) of 1 gm be ₹1.
⇒ Total CP for 1000 gm = ₹1000.
⇒ Shopkeeper sells it at 4% profit ⇒ Selling Price (SP) = 1000 × (104 / 100) = ₹1040.
⇒ However, the shopkeeper gives only 940 gm ⇒ Actual cost to shopkeeper = ₹940.
⇒ Profit = SP − Actual CP = 1040 − 940 = ₹100.
⇒ Actual Profit % = (Profit / Actual CP) × 100
⇒ Actual Profit % = (100 / 940) × 100 = 1000 / 94
⇒ Actual Profit % ≈ 10.638%
∴ The correct answer is 10.64%.
Additional Information
Dishonest Dealer Formula
Profit % = [(True Weight − False Weight) / False Weight] × 100. When sold at profit 'p%', overall profit = [{(100+p)/100 × (True/False)} − 1] × 100.
Successive Discounts
If two successive discounts d1% and d2% are given, the equivalent discount = (d1 + d2 − d1d2/100)%.
Marked Price and CP Relation
MP / CP = (100 + Profit%) / (100 − Discount%). This is useful for finding the markup percentage.