document.write( "Question 113310: Sam's annual interest from an investment iss 225. If Sam had invested $600 more at an annual interest rate that was 1% less, the annual interest would have been $234. What are the amount and rate of his actual investment?
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Algebra.Com's Answer #82448 by stanbon(75887)\"\" \"About 
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Sam's annual interest from an investment is 225. If Sam had invested $600 more at an annual interest rate that was 1% less, the annual interest would have been $234. What are the amount and rate of his actual investment?
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\n" ); document.write( "Interest = Prt; in your problem t=1
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\n" ); document.write( "EQUATIONS:
\n" ); document.write( "225 = Pr
\n" ); document.write( "234 = (P+600)(r-1)
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\n" ); document.write( "234 = Pr -P + 600r -600
\n" ); document.write( "234 = 225 -P + 600r -600
\n" ); document.write( "609 = -P + 600r
\n" ); document.write( "P -600r+609 = 0
\n" ); document.write( "But r = 225/P:
\n" ); document.write( "P -[600*225/P]+609 = 0
\n" ); document.write( "Multiply thru by P to get:
\n" ); document.write( "P^2 +609P - (600*225) = 0
\n" ); document.write( "Use the Quadratic Formula to solve for P:
\n" ); document.write( "P = [-609 +- sqrt(609^2 -4*(-600*225)]/2
\n" ); document.write( "P = [-609 + 954.4]/2
\n" ); document.write( "P = $172.70
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\n" ); document.write( "r = 225/P = 0.768
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\n" ); document.write( "Cheers,
\n" ); document.write( "Stan H.
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