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Math Help - percentage

  1. #1
    Senior Member
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    Aug 2009
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    percentage

    ok so here is the problem....

    the price of a music cd was first increased by 15 percent and then the new price was decreased by 30 percent. the final price was what percent of the initial price?

    ok so to do this problem i set up my notation...

    C = price of cd

    ok so then i said....

    (C +.15C) = new price

    new price = N

    N-.3N or...

    (C+.15C)-.3(C+.15C)=.76C

    i dunno my book says this is wrong, but im not sure where i went wrong...

    any help would be appreciated, thanks!
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  2. #2
    Senior Member
    Joined
    Aug 2009
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    Re: percentage

    nevermind i see what i did wrong...so it seems i need to review addition, subtraction and multiplication....lol

    the correct answer was or is .805

    this problem was taken from dr chung perfect sat math page 49 #2, just in case anyone wants to follow up or whatever...
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  3. #3
    MHF Contributor
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    Re: percentage

    d = decrease, i = increase
    So you realised that: (1-d)(1+i) = (1-.30)(1+.15) = .70(1.15) = .805 = 80.5%
    Right?
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