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anonymous

  • 5 years ago

Linda invests $13,000 for one year. Part is invested at 4%, another part at 5%, and the rest at 7%. The total income from all 3 investments is $705. The combined income from the 4% and 5% investments is $75 more than the income from the 7% investment. Find the amount invested at each rate (can somebody please help me solve this problem, i am completely lost)

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  1. anonymous
    • 5 years ago
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    cant be too bad

  2. anonymous
    • 5 years ago
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    let amount invested at 4% be x ammount at 5% be y amount at 7% be z

  3. anonymous
    • 5 years ago
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    we know that the total amount invested is 13000 so x+y+z = 13000 ( one eqn )

  4. anonymous
    • 5 years ago
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    now, assuming simple interest ( which I think is what they want )

  5. anonymous
    • 5 years ago
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    I = Prn

  6. anonymous
    • 5 years ago
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    income from $x = x (0.04)(1) =0.04x

  7. anonymous
    • 5 years ago
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    x*1.04+y*1.05=z*1.07 With only one year it has to be simple interest.

  8. anonymous
    • 5 years ago
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    so ^ thats another eqn there

  9. anonymous
    • 5 years ago
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    and last condition gives another eqn 0.04x +0.05y = 75 + 1.07z

  10. anonymous
    • 5 years ago
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    lol that guys eqn was wrong

  11. anonymous
    • 5 years ago
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    yeah it was, sorry, fiddling about now

  12. anonymous
    • 5 years ago
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    should have been 0.04x + 0.05y + 0.07z = 705

  13. anonymous
    • 5 years ago
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    so x+y+z = 13000 0.04x + 0.05y + 0.07z = 705 0.04x +0.05y = 75 + 1.07z

  14. anonymous
    • 5 years ago
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    there eqns, three unknowns you can solve, im not doing boring pointless albegra

  15. anonymous
    • 5 years ago
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    algebra

  16. anonymous
    • 5 years ago
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    no EDIT : x+y+z = 13000 0.04x + 0.05y + 0.07z = 705 0.04x +0.05y = 75 + 0.07z made a little mistake when copying the second eqn

  17. anonymous
    • 5 years ago
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    they should have it so you can delete posts z :| also, if you were to want to solve these eqns, the best first step would be to subtract eqns 2 and 3

  18. anonymous
    • 5 years ago
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    yeah just word problems arent my thing :(

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