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Math Help - Word Problem for Algebra.

  1. #1
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    Word Problem for Algebra.

    Shawn Hetrick has an annual interest income of $3290 from two investments. He has $7000 more invested at 8% than he has invested at 6%. find the amount invested at each rate.
    Can anyone solve this for me? I'm a bit confused.. Well not really, more like I'm stuck. The problem I have is that this question doesn't give to total he invested on the 8% and 6%. I just can't think of an equation for this.
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  2. #2
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    one equation could be
    x=amount invested in 8%
    y=amount invested in 6%
    0.08x+0.06y=3290
    find the other equation then use elimination method to eliminate x and find y then use one of the equations to plug in y and find x
    other equation is something like
    x+7000=y
    which equals to:
    x-y=7000
    then just use simple elimination and u shall find the answer
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  3. #3
    Super Member 11rdc11's Avatar
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    .08(x+7000) + .0 6(x) = 3290
    Last edited by 11rdc11; August 24th 2009 at 07:29 PM. Reason: typo, hard to type on the playstation
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  4. #4
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    Quote Originally Posted by 11rdc11 View Post
    .8(x+7000) + .6(x) = 3290
    0.8 is 80% while 0.08 is 8%
    so you were wrong the the right equation is still
    <br /> <br />
0.08x+0.06y=3290<br />
    and
    <br /> <br />
x-y=7000<br />
    now just use those 2 to solve it with elimination
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  5. #5
    Super Member 11rdc11's Avatar
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    Quote Originally Posted by saar4ever View Post
    0.8 is 80% while 0.08 is 8%
    so you were wrong the the right equation is still
    <br /> <br />
0.08x+0.06y=3290<br />
    and
    <br /> <br />
x-y=7000<br />
    now just use those 2 to solve it with elimination
    Thanks for spotting that. I used the equation I did incase he or she does not know how to work with 2 variables
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  6. #6
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    Sweet, thanks guys! I can see the picture of it I still need more practice.
    The thing is that I have is making an equation out of a word problem
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  7. #7
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    How about this one
    A freight train travels 60 miles in the same time that a passenger train travels 100miles. If the passenger train goes 30miles per hour faster than the freight train, find the rate of each.

    Honestly, I don't have an idea of what this question is trying to ask.
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  8. #8
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    Quote Originally Posted by saar4ever View Post
    0.8 is 80% while 0.08 is 8%
    so you were wrong the the right equation is still
    <br /> <br />
0.08x+0.06y=3290<br />
    and
    <br /> <br />
x-y=7000<br />
    now just use those 2 to solve it with elimination
    Don't solve it for me but can you give me a brief explain of x and y using in an equation? I'm only use to working with x Yet, I'm in a community college learning algebra.
    Sorry for the trouble and thanks for helping me out, I'm still a newb.
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  9. #9
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    multiply this by 100
    <br /> <br />
0.08x+0.06y=3290<br />
    =
    <br /> <br />
8x+6y=329000<br />
    then divide by 6 and add equation 1 and 2
    then u have x all alone and divide it to find what it is
    then plug in x into the second equation to find out what y is
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  10. #10
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    Quote Originally Posted by BrilliantLegacy View Post
    How about this one
    A freight train travels 60 miles in the same time that a passenger train travels 100miles. If the passenger train goes 30miles per hour faster than the freight train, find the rate of each.

    Honestly, I don't have an idea of what this question is trying to ask.
    60x=100y
    x=y+30

    then

    60x-100y=0
    x-y=30

    then

    -0.6x+y=0
    x-y=30

    0.4x=30

    x=75mph
    y=45mph
    just double checked pretty sure its right answer
    hope it makes sense
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  11. #11
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    Quote Originally Posted by saar4ever View Post
    60x=100y
    x=y+30

    then

    60x-100y=0
    x-y=30

    then

    -0.6x+y=0
    x-y=30

    0.4x=30

    x=75mph
    y=45mph
    just double checked pretty sure its right answer
    hope it makes sense
    Thanks a lot dude. I have a pre-test tomorrow and you have just saved me!
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  12. #12
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    your welcome no prob
    see ya
    gl on the test hope u ace it
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  13. #13
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    Quote Originally Posted by saar4ever View Post
    your welcome no prob
    see ya
    gl on the test hope u ace it
    Do you mind telling me the the answer for the first one? I want to make sure I have it right.
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  14. #14
    Super Member 11rdc11's Avatar
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    Quote Originally Posted by saar4ever View Post
    60x=100y
    x=y+30

    then

    60x-100y=0
    x-y=30

    then

    -0.6x+y=0
    x-y=30

    0.4x=30

    x=75mph
    y=45mph
    just double checked pretty sure its right answer
    hope it makes sense
    I got a different answer. Speeds are 75 and 105. The passenger should be faster

    x=y-30 or x+30=y
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  15. #15
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    Quote Originally Posted by 11rdc11 View Post
    I got a different answer. Speeds are 75 and 105. The passenger should be faster

    x=y-30 or x+30=y
    could be need to check it again
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