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Math Help - hai help plz

  1. #1
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    hai help plz

    One kind of hard candy sells for 89 cent per kilogram. Another sells for $1.10
    per kilogram. How many kilograms of each kind will be used for 30 kilograms of a mixture to sell for 96 cent per kilogram?


    How many millileters of vinegar must be added to 20 milliters of a 10%-vineger solution to make it a 25% vinegar solution?

    How would I solve these?
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  2. #2
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    Quote Originally Posted by Aarxn
    One kind of hard candy sells for 89 cent per kilogram. Another sells for $1.10
    per kilogram. How many kilograms of each kind will be used for 30 kilograms of a mixture to sell for 96 cent per kilogram?
    Let us say you sell x kilograms of candy which goes for .89 and y kilograms of candy which goes for 1.10 then the total price is,
    .89x+1.1y=30(.96)=28.8
    and the total amout is,
    x+y=30
    In this equation solve for "y",
    y=30-x thus, substitute that into the first equation,
    .89x+1.1(30-x)=28.8
    Open parantheses,
    .89x+33-1.1x=28.8
    Subtract 33 from both sides and combine "x" terms,
    -.21x=-4.2
    Divide both sides by (-.21) thus,
    x=20 thus, y=10
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  3. #3
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    Quote Originally Posted by Aarxn
    How many millileters of vinegar must be added to 20 milliters of a 10%-vineger solution to make it a 25% vinegar solution?
    Here is the formula,
    \mbox{concetration}=\frac{\mbox{amout of substance}}{\mbox{total amount present}}

    You have 20 milliletrs of 10% vineger solution. Meaning 10% of 20 is vineger thus, 2 milliletrs of vineger. You add m millileters to get a concentration of 25% meaning,
    \frac{2+m}{20+m}=.25
    Note, and understand why the numerator is the way it is and the denominator is the way is it.

    Now cross mutiply considering .25 as a fraction 1/4 thus,
    4(2+m)=20+m
    Thus,
    8+4m=20+m
    Subtract 8 and m from both sides,
    3m=12
    Thus,
    m=4\mbox{ millilters} need to be added.
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  4. #4
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    Quote Originally Posted by ThePerfectHacker
    Here is the formula,
    \mbox{concetration}=\frac{\mbox{amout of substance}}{\mbox{total amount present}}

    You have 20 milliletrs of 10% vineger solution. Meaning 10% of 20 is vineger thus, 2 milliletrs of vineger. You add m millileters to get a concentration of 25% meaning,
    \frac{2+m}{20+m}=.25
    Note, and understand why the numerator is the way it is and the denominator is the way is it.

    Now cross mutiply considering .25 as a fraction 1/4 thus,
    4(2+m)=20+m
    Thus,
    8+4m=20+m
    Subtract 8 and m from both sides,
    3m=12
    Thus,
    m=4\mbox{ millilters} need to be added.
    Hey, thank you for helping me.
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