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Math Help - working out the percentage!

  1. #1
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    working out the percentage!

    hi this is my question:
    In a sale the price of a digital radio decreases from 75 to 66.
    work out the percentage decrease in price.

    im not sure but would it be 72.53%?? if that is wrong can anyone help me please?
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  2. #2
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    Quote Originally Posted by andyboy179 View Post
    hi this is my question:
    In a sale the price of a digital radio decreases from 75 to 66.
    work out the percentage decrease in price.

    im not sure but would it be 72.53%?? if that is wrong can anyone help me please?

    The "decrease" in sterling is 75-66=9

    This is a decrease of 9 from 75,

    so you must express this decrease as a percentage of 75

    The fraction is \frac{9}{75}

    A percentage is the fraction multiplied by 100

    (remember \frac{1}{2} is 50%).

    How did you calculate 72.53% ?
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  3. #3
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    at school it is called the 1 method, we start with 1 and with this question is it decrease by 9 so it would be x0.91 then you use the starting price and / by 0.91 = 82%
    (i messed up the first answer i put which was 72.53%)

    working out the percentage!-untitled7.jpg
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  4. #4
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    Quote Originally Posted by andyboy179 View Post
    at school it is called the 1 method, we start with 1 and with this question is it decrease by 9 so it would be x0.91 then you use the starting price and / by 0.91 = 82%
    (i messed up the first answer i put which was 72.53%)

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    75 decreases by 9

    \frac{75}{100}=0.75

    So 100 would decrease by 9\left(\frac{1}{0.75}\right)=\frac{9}{0.75}=12

    100 would decrease by more so you put the 1 on top of the fraction and 0.75 underneath.

    That's a 12% decrease
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