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David owns a plot worth тВ╣10,000. He sells it to Rodney at 10% profit. Rodney sells the plot back to David at a loss of 10%. In the whole transaction, Rodney realises ________.
no profit no loss
loss of тВ╣1,000
profit of тВ╣2,000
loss of тВ╣1,100
loss of тВ╣1,100
Rodney buys the plot from David for 1.1 ├Ч 10,000 = 11,000 and sells it back to David for 0.9 ├Ч 11,000 = 9,900. His loss is 11,000 - 9,900 = 1,000.
Initial plot worth = тВ╣10,000. David sells to Rodney at 10% profit. Rodney sells back to David at 10% loss.
P=CP├Ч100100+profit%тАЛ, L=CP├Ч100100тИТloss%тАЛ
Rodney buys the plot from David for 1.1 ├Ч 10,000 = 11,000 and sells it back to David for 0.9 ├Ч 11,000 = 9,900. His loss is 11,000 - 9,900 = 1,000.
Students often assume no profit no loss because the percentages are the same, forgetting the base value changes after the first transaction.
Calculate Rodney's Cost Price
David sells the plot worth тВ╣10,000 to Rodney at 10% profit. Rodney's cost price CPRodneyтАЛ is: 10,000├Ч(1+0.10)=11,000
CPRodneyтАЛ=11,000
Calculate Rodney's Selling Price
Rodney sells the plot back to David at a 10% loss. His selling price SPRodneyтАЛ is: 11,000├Ч(1тИТ0.10)=9,900
SPRodneyтАЛ=9,900
Calculate Rodney's Profit/Loss
Since SPRodneyтАЛ<CPRodneyтАЛ, Rodney incurs a loss. Loss = CPRodneyтАЛтИТSPRodneyтАЛ=11,000тИТ9,900=1,000.
Loss=1,000
D is correct because Rodney bought the plot for тВ╣11,000 and sold it for тВ╣9,900, resulting in a loss of тВ╣1,000.
This concept is a variation of the successive percentage change formula a+b+100abтАЛ. Here, a=10,b=тИТ10, so 10тИТ10тИТ100100тАЛ=тИТ1%. 1% of 10,000 is 100, but since Rodney's base was 11,000, 10% loss on 11,000 is 1,100.