document.write( "Question 248918: How long would it take for an amount of money invested at an annual rate of 6% compounded semiannually, to triple? \n" ); document.write( "
Algebra.Com's Answer #181371 by Theo(13342)\"\" \"About 
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future value is 3
\n" ); document.write( "present amount is 1
\n" ); document.write( "annual interest rate is 6%\r
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\n" ); document.write( "\n" ); document.write( "6% / 2 = 3% every half a year.\r
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\n" ); document.write( "\n" ); document.write( "interest rate equals interest rate percent divided by 100% = .03 every half a year.\r
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\n" ); document.write( "\n" ); document.write( "the formula you need is:\r
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\n" ); document.write( "\n" ); document.write( "3 = 1 * (1.03)^x\r
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\n" ); document.write( "\n" ); document.write( "you need to solve for x.\r
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\n" ); document.write( "\n" ); document.write( "formula becomes:\r
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\n" ); document.write( "\n" ); document.write( "3 = (1.03)^x\r
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\n" ); document.write( "\n" ); document.write( "take the log of both sides of the equation to get:\r
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\n" ); document.write( "\n" ); document.write( "log(3) = log((1.03)^2)\r
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\n" ); document.write( "\n" ); document.write( "by the rules of logarithms, this equation becomes:\r
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\n" ); document.write( "\n" ); document.write( "log(3) = x*log(1.03)\r
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\n" ); document.write( "\n" ); document.write( "divide both sides of this equation by log(1.03) to get:\r
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\n" ); document.write( "\n" ); document.write( "x = log(3)/log(1.03)\r
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\n" ); document.write( "\n" ); document.write( "solve for x to get:\r
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\n" ); document.write( "\n" ); document.write( "x = 37.16700967\r
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\n" ); document.write( "\n" ); document.write( "this means that it would take 37.16700967 half years to triple your money.\r
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\n" ); document.write( "\n" ); document.write( "divide this by 2 to get:\r
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\n" ); document.write( "\n" ); document.write( "18.58350483 years.\r
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\n" ); document.write( "\n" ); document.write( "We required half years because our interest rate was every half a year (semi-annually).\r
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\n" ); document.write( "\n" ); document.write( "these would be called semi-annual time periods.\r
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\n" ); document.write( "\n" ); document.write( "there are 37.16700967 semi-annual time periods which equate to 18.58350483 years.\r
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