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Original investment of $17,000 at two interest rates.  Rate one interest after 1 year...

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joshualyn | eNotes Newbie

Posted October 21, 2013 at 7:03 PM via web

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Original investment of $17,000 at two interest rates.  Rate one interest after 1 year is I(x) = -.005x +425, where x is interest at 2.0%.  Rate two is at 2.5% and the total interest for both is $409.  What is interest earned for both certificates?

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aruv | High School Teacher | Valedictorian

Posted October 22, 2013 at 6:01 AM (Answer #1)

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Given

I(x)=409    (i)

But

I(x)=-.005x+425      (ii)

From (i) and (ii), we have

409=-.005x+425

.005x=425-409

.005x=16

x=16/(.005)

x=3200

Thus 

$3200 invested at rate of 2.0% and $13800 invested at rate of 2.5% .

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