document.write( "Question 703336: How many years will it take for a $100 investment to grow to $700 if it is compounded continuously at a rate of 9%?
\n" ); document.write( "A(t)= P*e^rt
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Algebra.Com's Answer #433443 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 formula.\r
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\n" ); document.write( "\n" ); document.write( "\"700=100%2Ae%5E%280.09%2At%29\" Plug in \"A=700\", \"P=100\", and \"r=0.09\" (the decimal equivalent of 9%).\r
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\n" ); document.write( "\n" ); document.write( "\"700%2F100=e%5E%280.09%2At%29\" Divide both sides by \"100\".\r
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\n" ); document.write( "\n" ); document.write( "\"7=e%5E%280.09%2At%29\" Evaluate \"700%2F100\" to get \"7\".\r
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\n" ); document.write( "\n" ); document.write( "\"ln%287%29=ln%28e%5E%280.09%2At%29%29\" Take the natural log of both sides.\r
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\n" ); document.write( "\n" ); document.write( "\"ln%287%29=0.09%2At%2Aln%28e%29\" Pull down the exponent using the identity \"ln%28x%5Ey%29=y%2Aln%28x%29%29\".\r
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\n" ); document.write( "\n" ); document.write( "\"ln%287%29=0.09%2At%2A1\" Evaluate the natural log of 'e' to get 1.\r
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\n" ); document.write( "\n" ); document.write( "\"ln%287%29=0.09%2At\" Multiply and simplify.\r
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\n" ); document.write( "\n" ); document.write( "\"1.94591014905531=0.09%2At\" Evaluate the natural log of \"7\" to get \"1.94591014905531\" (this value is approximate).\r
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\n" ); document.write( "\n" ); document.write( "\"1.94591014905531%2F0.09=t\" Divide both sides by \"0.09\" to isolate 't'.\r
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\n" ); document.write( "\n" ); document.write( "\"21.6212238783924=t\" Evaluate \"1.94591014905531%2F0.09\" to get \"21.6212238783924\".\r
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\n" ); document.write( "\n" ); document.write( "\"t=21.6212238783924\" Flip the equation.\r
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\n" ); document.write( "\n" ); document.write( "\"t=22\" Round to the nearest whole year.\r
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\n" ); document.write( "\n" ); document.write( "So it will take about 22 years.
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