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Math Help - PERCENTAGES

  1. #1
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    PERCENTAGES

    when easy pc sell computers at their normal prices, it makes a profit of 30%. In a sale, normal prices are reduced by 10%. Calculate the percentage profit on a computer sold in the sale? cheers
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  2. #2
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    Solution

    when easy pc sell computers at their normal prices, it makes a profit of 30%. In a sale, normal prices are reduced by 10%. Calculate the percentage profit on a computer sold in the sale? cheers

    Well, say Easy PC sells a computer for price x. Then if it makes a profit of 30%, then it can be expressed as 0.30*x. Now, when the normal price is reduced by 10%, it can be expressed as x - 0.10*x = 0.90*x

    You can then set up a ratio to determine the profit made when the PC is on sale:

    x/.30x = .90x/(y*x) with x denoting original price and y denoting percentage of profit made when PC is on sale.

    Cancel out all x's to get:

    1/30 = .90/y. Cross multiply to get:

    y = 30*.90
    y = 0.27

    So, when the PC is on sale, Easy PC will make 27% profit on each PC sold.
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  3. #3
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    thank you ajj86, but when i checked the answer section at the back of my book it says 17 percent? could they have got this wrong?

    Quote Originally Posted by ajj86 View Post
    when easy pc sell computers at their normal prices, it makes a profit of 30%. In a sale, normal prices are reduced by 10%. Calculate the percentage profit on a computer sold in the sale? cheers

    Well, say Easy PC sells a computer for price x. Then if it makes a profit of 30%, then it can be expressed as 0.30*x. Now, when the normal price is reduced by 10%, it can be expressed as x - 0.10*x = 0.90*x

    You can then set up a ratio to determine the profit made when the PC is on sale:

    x/.30x = .90x/(y*x) with x denoting original price and y denoting percentage of profit made when PC is on sale.

    Cancel out all x's to get:

    1/30 = .90/y. Cross multiply to get:

    y = 30*.90
    y = 0.27

    So, when the PC is on sale, Easy PC will make 27% profit on each PC sold.
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  4. #4
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    Response

    Well, I don't think the back of the book has ever been wrong for me. I'm going to try to rework the problem through a few times.
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  5. #5
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    30% profit x 90% of price before sale
    =1.30 x 0.9
    =1.17
    therefore 17%profit
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