Explanation
Assume originally:
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Bought 100 items for Rs.100
So, Cost Price (CP) per item = Rs.1
Now buys 10% less:
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10% less than 100 = 90 items
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Still spends Rs.100
So new CP per item:
CP= 100/90
Now sells 10% more:
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10% more than 100 = 110 items
Assume selling rate is Rs.1 per item.
So total Selling Price:
SP=110×1=110
Profit:
Profit=SP−CP=110−100=10
Profit percentage formula:
Profit %= Profit/ Cost Price ×100
Substitute values:
10/100×100=10%
That approach looks tempting, but it ignores that buying fewer changes the cost per item. The correct combined effect is:
Profit %=(110/90−1)×100
(110/90−1)×100
=(20/90)×100=22.22%
Last updated question by NS on 2 MAY 2026