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Math Help - % Decrease in price

  1. #1
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    % Decrease in price

    If a compact disc that usually sells for $12.95 is on sale for $9.95, then what is the percent decreast in price, rounded to the nearest whole number?

    I was not sure of the formula...but I did come out using my common sense after my equation to an answer of 23%. I did the following

    % decrease = (decrease amount / original amout ) * 100%
    % decrease = (9.95 / 12.95) * 100%
    % decrease = .77 or 77%

    then

    I just used common sense to know it must be 23%...but what equation could I use?
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  2. #2
    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by thecapaccino View Post
    If a compact disc that usually sells for $12.95 is on sale for $9.95, then what is the percent decreast in price, rounded to the nearest whole number?

    I was not sure of the formula...but I did come out using my common sense after my equation to an answer of 23%. I did the following

    % decrease = (decrease amount / original amout ) * 100%
    % decrease = (9.95 / 12.95) * 100%
    % decrease = .77 or 77%

    then

    I just used common sense to know it must be 23%...but what equation could I use?
    yes, it should be 23%

    there are many approaches to a problem like this. but if you want a straightforward formula, here it is:

    this will work for increases or decreases

    %change = (change in amount / original amount)*100%

    so for your question:
    %decrease = ([12.95 - 9.95]/12.95) * 100%
    = 3/12.95 * 100%
    = 23%
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  3. #3
    is up to his old tricks again! Jhevon's Avatar
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    what you did was to find what percentage of the original is the decreased amount, but the question asked for what percentage of the amount is the decrease.

    you could in fact use your method but know that you have to subtract the answer from 100% when done
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