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A trader claims to sell goods at a 10% profit but uses a weight that is 20% less than the actual weight. Find the total percentage of profit earned.
30%
35%
37.5%
40%
37.5%
Use the ratio of selling price to cost price: (100110тАЛ)├Ч(80100тАЛ)=811тАЛ. The profit is (811тИТ8тАЛ)├Ч100=37.5%.
Claimed profit = 10%, Weight used = 20% less than actual weight.
Total┬аProfit=(1тИТLoss2тАЛ1+Profit1тАЛтАЛтИТ1)├Ч100%
Use the ratio of selling price to cost price: (100110тАЛ)├Ч(80100тАЛ)=811тАЛ. The profit is (811тИТ8тАЛ)├Ч100=37.5%.
Students often add the percentages (10% + 20% = 30%) without accounting for the fact that the cost price of the goods sold is reduced due to the underweight.
Define the reference base
Assume the actual cost price of 100 units of weight is 100.
Actual┬аweight=100,Cost=100
Calculate the Selling Price
The trader claims a 10% profit on the original cost, so the selling price is 100+10=110.
Selling┬аPrice┬а(SP)=110
Calculate the effective Cost Price
Since the trader uses 20% less weight, they are only supplying 80 units for the cost of 80.
Effective┬аCost┬аPrice┬а(CP)=100тИТ20=80
Calculate percentage profit
Profit is the difference between SP and effective CP relative to the effective CP: 80110тИТ80тАЛ├Ч100.
Profit=8030тАЛ├Ч100=37.5%
C is correct because the ratio of the effective selling price to the effective cost price leads to a total profit of 37.5%.
This concept of effective pricing is similar to 'Successive Percentage Changes' and 'Mixture & Alligation' problems involving volume or mass substitution.