document.write( "Question 508311: Part of a $10,000 investment earned an interest rate of 7%, and the rest earned interest at a rate of 9%. The combined interest earned at the end of 1 year was $732. How much was invested at each rate? \n" ); document.write( "

Algebra.Com's Answer #340957 by mananth(16946) $\"\"$ $\"About$

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Investment II 7.00% per annum ---x
\n" ); document.write( "Investment II 9.00% per annum ---y
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\n" ); document.write( "x + y= 10000 ------------------------1
\n" ); document.write( "7.00%x +9.00%y = $732.00
\n" ); document.write( "Multiply by 100
\n" ); document.write( "7x+9y = $73,200.00 --------2
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\n" ); document.write( "Multiply (1) by -7
\n" ); document.write( "we get
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\n" ); document.write( "-7 x -7 y = -70000.00
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\n" ); document.write( "Add this to (2)
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\n" ); document.write( "0 x 2 y = $3,200.00
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\n" ); document.write( "divide by 2
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\n" ); document.write( " y = $1,600.00 investment at
\n" ); document.write( "Balance $8,400.00 investment at
\n" ); document.write( "CHECK
\n" ); document.write( "$8,400.00 --------- 7.00% ------- $588.00
\n" ); document.write( "$1,600.00 ------- 9.00% ------- $144.00
\n" ); document.write( "Total ------- $732.00
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