document.write( "Question 127467: Mary wants her $9000 GIC to double in value in nine years. What annual rate of interest is required for her to reach her goal. Assume interest is compounded annually. \n" ); document.write( "
Algebra.Com's Answer #93429 by ankor@dixie-net.com(22740)\"\" \"About 
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Mary wants her $9000 GIC to double in value in nine years. What annual rate of interest is required for her to reach her goal. Assume interest is compounded annually.
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\n" ); document.write( "Let r = decimal value of the interest required
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\n" ); document.write( "Using the annual interest equation: A = Ao*(1+r)^t
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\n" ); document.write( "9000 * (1 + r)^9 = 18000
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\n" ); document.write( "(1 + r)^9 = 18000/9000; divided both sides by 9000
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\n" ); document.write( "(1 + r)^9 = 2
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\n" ); document.write( "9 * ln(1+r) = .693
\n" ); document.write( "ln(1 + r) = \".693%2F9\"
\n" ); document.write( "ln(1 + r) = .077
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\n" ); document.write( "Find the antilog (e^x) of both sides
\n" ); document.write( "1 + r = 1.08
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\n" ); document.write( "r = 1.08 - 1
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\n" ); document.write( "r = .08 which is 8%
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\n" ); document.write( "Check solution using a calc
\n" ); document.write( "1.08^9 * 9000 = 17991 ~ 18000 \n" ); document.write( "
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