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Math Help - Applicaton Question

  1. #1
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    Linear Applicaton Problem

    I'm back*


    Having a bit of difficulty with some application word problems... one in particular has me confused.*


    I know the following:
    SPD=\frac{D}{T}


    DIST=SPD\cdot TIME


    TIME=\frac{D}{S}


    The question:
    A plane averaging 120mi/hr and an express train averaging 60mi/hr depart at the same time from the same city headed for the same destination. If the train arrives 45 minutes later than the plane, how far did they each travel?


    ----*


    Also having some difficulty making sense of this:*
    A farmer wants to enclose a rectangular area next to a river. No fence is used on the side of the area next to the river. If the farmer has 180 ft of fencing and wants the length of the area to be 50 ft longer than the width, find the dimensions of the fenced area.


    Perimeter = 2l \cdot 2w


    If I solve for a complete fence line:
    2(x+50)+2x=180 ... the problem doesn't work out obviously... I'm looking for some great explanations to help figure this out.*
    Last edited by pychon; September 21st 2010 at 07:25 PM.
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  2. #2
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    A plane averaging 120mi/hr and an express train averaging 60mi/hr depart at the same time from the same city headed for the same destination. If the train arrives 45 minutes later than the plane, how far did they each travel?

    Let time by plane = h; then time by train = h + 3/4
    120h = 60(h + 3/4) ; solve for h, then get distance.

    A farmer wants to enclose a rectangular area next to a river. No fence is used on the side of the area next to the river. If the farmer has 180 ft of fencing and wants the length of the area to be 50 ft longer than the width, find the dimensions of the fenced area.

    You're using 4 sides, but fence will cover only 3 sides...try again!
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  3. #3
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    Quote Originally Posted by Wilmer View Post

    You're using 4 sides, but fence will cover only 3 sides...try again!
    Yes, I know I'm using 4 sides... 2L x 2W will not work... if I solve it as noted above x+50+2x=180 (being there is only 1 length) it doesn't check. Which is why I've asked for an explanation how to solve it better or understand.
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  4. #4
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    w = width; then length = w+50
    2w + w+50 = 180
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  5. #5
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    Quote Originally Posted by Wilmer View Post
    w = width; then length = w+50
    2w + w+50 = 180
    ... nvm, it would help to write down 180 instead of 160.
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  6. #6
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    double post
    Last edited by pychon; September 21st 2010 at 10:07 PM.
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