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If the price of milk is 15% more than that of water, then the price of water is approximately what percentage less than that of milk?
5%
7.5%
10.50%
13.04%
13.04%
Use the formula 100+rrтАЛ├Ч100 where r is the percentage increase. For r=15, this is 11515тАЛ├Ч100=233тАЛ├Ч100тЙИ13.04%.
Price of milk is 15% more than the price of water.
Percentage=(100+xxтАЛ)├Ч100
Use the formula 100+rrтАЛ├Ч100 where r is the percentage increase. For r=15, this is 11515тАЛ├Ч100=233тАЛ├Ч100тЙИ13.04%.
Many students wrongly assume the answer is 15%, failing to account for the change in the base (denominator) from 'price of water' to 'price of milk'.
Define the base price
Assume the price of water is 100 units.
PwaterтАЛ=100
Calculate the price of milk
Since milk is 15% more than water, add 15% of 100 to the base price.
PmilkтАЛ=100+15=115
Calculate the percentage difference
To find how much less water is than milk, find the difference relative to the price of milk.
Percentage=11515тАЛ├Ч100=233тАЛ├Ч100тЙИ13.04%
D is correct because the price of water relative to the price of milk is (15/115)├Ч100, which equals approximately 13.04%.
This concept is fundamental in Profit & Loss (e.g., mark-up vs discount percentage) and Speed-Time-Distance problems involving speed variations.