document.write( "Question 1146612: Using simple interest, a foundation invests ​$65,000: a part at 7​%, twice that amount at 4​%, and the rest at 5.5​%. What is the most that the foundation can invest at 4​% and be guaranteed ​$3500 in interest per​ year?
\n" ); document.write( "The foundation can invest at most ​____ at 4​%.
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Algebra.Com's Answer #767939 by VFBundy(438)\"\" \"About 
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7% interest account:
\n" ); document.write( "Principal = p/2
\n" ); document.write( "Rate = 0.07
\n" ); document.write( "Interest = 0.07p/2 = 0.035p
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\n" ); document.write( "4% interest account:
\n" ); document.write( "Principal = p
\n" ); document.write( "Rate = 0.04
\n" ); document.write( "Interest = 0.04p
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\n" ); document.write( "5.5% interest account:
\n" ); document.write( "Principal = 65000 - p/2 - p
\n" ); document.write( "Rate = 0.055
\n" ); document.write( "Interest = 0.055(65000 - p/2 - p) = 3575 - 0.0275p - 0.055p = 3575 - 0.0825p
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\n" ); document.write( "0.035p + 0.04p + (3575 - 0.0825p) >= 3500
\n" ); document.write( "
\n" ); document.write( "-0.0075p + 3575 >= 3500
\n" ); document.write( "
\n" ); document.write( "-0.0075p >= -75
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\n" ); document.write( "p <= 10000
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\n" ); document.write( "4% interest:
\n" ); document.write( "Principal = p <= 10000
\n" ); document.write( "
\n" ); document.write( "The most you can invest in the 4% interest account is $10,000. \n" ); document.write( "
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