Algebra.Com's Answer #835675 by ikleyn(52850)![\"\"](\"/images/stars/stars-13.gif\")  
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document.write( "Find the time required for an investment of 5000 dollars to grow to 7100 dollars
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document.write( "at an interest rate of 7.5 percent per year, compounded quarterly.
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document.write( "Use the formula for the quarterly compounded account\r\n" );
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document.write( " F =  (1)\r\n" );
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document.write( "where\r\n" );
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document.write( " F = future value\r\n" );
document.write( " A = present value (the starting deposit)\r\n" );
document.write( " r = annual interest rate expressed as a decimal\r\n" );
document.write( " n = number of quarters\r\n" );
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document.write( "For the amount of $5000, compounded quarterly at 7.5%, the future value formula is\r\n" );
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document.write( " F =  \r\n" );
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document.write( "where n is the number of quarters.\r\n" );
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document.write( "Therefore, our equation to find \"n\" is\r\n" );
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document.write( " 7100 = \r\n" );
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document.write( "Divide both sides by 5000\r\n" );
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document.write( "  =  ,\r\n" );
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document.write( "or\r\n" );
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document.write( " 1.42 =  .\r\n" );
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document.write( "Take logarithm base 10 of both sides\r\n" );
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document.write( " log(1.42) = n*log(1.01875)\r\n" );
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document.write( "and find the number of quarters \"n\" using your calculator\r\n" );
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document.write( " n =  = 18.88 quarters.\r\n" );
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document.write( "Finally, round this value 18.88 quarters to the nearest greater integer number 19,\r\n" );
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document.write( "in order for the bank was in position to make the last compounding.\r\n" );
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document.write( "ANSWER. 19 quarters, or 4 years and 3 quarters (same as 4 years and 9 months).\r\n" );
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document.write( "Solved.\r
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document.write( "To see many other similar (and different) solved problems, look into the lesson\r
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document.write( " - Problems on discretely compound accounts \r
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document.write( "in this site, and learn the subject from there.\r
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document.write( "After reading this lesson, you will tackle such problems on your own without asking for help from outside.\r
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