A shopkeeper who weighs out less than he charges for is making a hidden profit — even when he claims to sell “at cost price”. The only catch is what you divide by.
Divide by what he actually gives
Faulty weight, selling at cost price: Gain% = weight givenerror×100, where error = claimed − given. A 800 g weight for 1 kg gives 800200 = 25%, not 20%.
• Buy X get Y free = effective discount X+YY×100. “Buy 3 get 1 free” = 41 = 25%.
• Buys at d% discount, sells at MP: profit% = 100−dd×100. A 20% buying discount is a 25% profit.
If a markup and a weight cheat both apply, they multiply — never add.
🪤Dishonest DealerSells at cost price, cheats on weight
true weight (g)
weight he gives (g)
He gives 800 g but charges for 1000 g.
Gain% = error ÷ (weight given) × 100
= (1000 − 800) ÷ 800 × 100
Gain = 25%
Giving 800 g for 1 kg at cost price: gain = 800200 × 100 = %.
📝Practice Questions
Q1A dealer uses a 900 g weight for 1 kg, selling at cost price. Gain%:
Q2"Buy 4 Get 1 Free" is an effective discount of:
Q3A dealer buys at 20% off MP ₹500 and sells at MP. Profit%:
📚
Real exam questions — Dishonest Dealer
3 question types · 9 solved examples from real SSC papers
Cheating on weight is a hidden profit measured on what is actually given, not on the kilogram charged for.
How to solve this type
The key idea: the dealer's real cost is only the weight that actually leaves his shop, while he charges the customer for the full claimed weight. So always put the weight he GIVES at the bottom (his cost base) and what he CHARGES on top — never divide by 1000 out of habit. When he sells at cost price (no markup) but uses a false weight, the whole gain is the missing grams: Gain%=true value−errorerror×100, where error = claimed weight − weight given. If he ALSO marks the price up (or down), the two effects multiply, not add: actual multiplier = weight given÷weight claimedprice factor.
A shopkeeper sells grain at his cost price per kg, but his weight gives only 800 g for every 1 kg. Find his profit%.
A20%B25%C16.67%D28%
A dishonest dealer claims to sell at cost price but uses a weight of 920 g for 1 kg. Find his gain% (to 2 decimal places).
A8.50%B8.70%C7.80%D9.20%
A trader sells rice at 8% profit on his marked rate but also gives 25% less weight than he charges for. Find his actual profit%.
