document.write( "Question 799240: You are going to invest $20, 000, part at 12% and part at 16%. What is the most that can be invested at 12% in order to make at least $3, 000 interest per year? \n" ); document.write( "

Algebra.Com's Answer #482566 by mananth(16946) $\"\"$ $\"About$

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Part I 16.00% per annum ------------- Amount invested =x
\n" ); document.write( "Part II 12.00% per annum ------------ Amount invested = y
\n" ); document.write( " 20000
\n" ); document.write( "Interest----- 3000.00
\n" ); document.write( "
\n" ); document.write( "Part I 16.00% per annum ---x
\n" ); document.write( "Part II 12.00% per annum ---y
\n" ); document.write( "Total investment
\n" ); document.write( "x + 1 y= 20000 -------------1
\n" ); document.write( "Interest on both investments
\n" ); document.write( "16.00% x + 12.00% y= 3000
\n" ); document.write( "Multiply by 100
\n" ); document.write( "16 x + 12 y= 300000.00 --------2
\n" ); document.write( "Multiply (1) by -16
\n" ); document.write( "we get
\n" ); document.write( "-16 x -16 y= -320000.00
\n" ); document.write( "Add this to (2)
\n" ); document.write( "0 x -4 y= -20000
\n" ); document.write( "divide by -4
\n" ); document.write( " y = 5000 - x)
\n" ); document.write( "Part I 16.00% $ 15000
\n" ); document.write( "Part II 12.00% $ 5000
\n" ); document.write( "
\n" ); document.write( "CHECK
\n" ); document.write( "15000 --------- 16.00% ------- 2400.00
\n" ); document.write( "5000 ------------- 12.00% ------- 600.00
\n" ); document.write( "Total -------------------- 3000.00
\n" ); document.write( "
\n" ); document.write( "m.ananth@hotmail.ca
\n" ); document.write( " \n" ); document.write( "

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