document.write( "Question 219555: what interest rate is required for an investment with continuously compounded interest to double in 6 years \n" ); document.write( "
Algebra.Com's Answer #165077 by jim_thompson5910(35256)\"\" \"About 
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\n" ); document.write( "\n" ); document.write( "\"A=Pe%5E%28rt%29\" Start with the continuous compounding interest formula.\r
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\n" ); document.write( "\n" ); document.write( "\"500=250%2Ae%5E%28r%2A6%29\" Plug in \"A=500\", \"P=250\", and \"t=6\".\r
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\n" ); document.write( "\n" ); document.write( "\"500=250%2Ae%5E%286%2Ar%29\" Rearrange the terms.\r
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\n" ); document.write( "\n" ); document.write( "\"500%2F250=e%5E%286%2Ar%29\" Divide both sides by \"250\".\r
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\n" ); document.write( "\n" ); document.write( "\"2=e%5E%286%2Ar%29\" Divide \"500%2F250\" to get \"2\".\r
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\n" ); document.write( "\n" ); document.write( "\"ln%282%29=ln%28e%5E%286%2Ar%29%29\" Take the natural log of both sides.\r
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\n" ); document.write( "\n" ); document.write( "\"ln%282%29=6%2Ar%2Aln%28e%29\" Pull down the exponent using the identity \"ln%28x%5Ey%29=y%2Aln%28x%29\".\r
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\n" ); document.write( "\n" ); document.write( "\"ln%282%29=6%2Ar%2A1\" Evaluate \"ln%28e%29\" to get \"1\".\r
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\n" ); document.write( "\n" ); document.write( "\"ln%282%29=6%2Ar\" Multiply.\r
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\n" ); document.write( "\n" ); document.write( "\"0.693147=6%2Ar\" Evaluate \"ln%282%29\" to get \"0.693147\"\r
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\n" ); document.write( "\n" ); document.write( "\"0.693147%2F6=r\" Divide both sides by \"6\" to isolate 'r'\r
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\n" ); document.write( "\n" ); document.write( "\"0.115525=r\" Divide \"0.693147%2F6\" to get \"0.115525\"\r
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\n" ); document.write( "\n" ); document.write( "\"r=0.115525\" Rearrange the equation.\r
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\n" ); document.write( "\n" ); document.write( "\"r=0.1155\" Round to the nearest ten-thousandth.\r
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\n" ); document.write( "\n" ); document.write( "So an interest rate of about 11.55% (don't forget to multiply by 100 to convert the decimal to a percent) will make the initial investment of $250 grow to $500 in 6 years.
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