document.write( "Question 1166208: A contract valued at $81500.00 requires payment of $2430.00 at the beginning of every 3 months. If interest is 6.5% compounded quarterly, calculate the term of this contract (round to years and months). \n" ); document.write( "
Algebra.Com's Answer #851392 by ikleyn(52781)\"\" \"About 
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\n" ); document.write( "A contract valued at $81500.00 requires payment of $2430.00 at the beginning of every 3 months.
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document.write( "This problem is about a sinking fund compounded quarterly.\r\n" );
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document.write( "The initial/starting value of the fund is $81,500. The fund makes outpayments\r\n" );
document.write( "of $2430 quarterly and is compounded quarterly at the annual rate of 6.5%.\r\n" );
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document.write( "They want to know the term of this contract, i.e. the number of quarters.\r\n" );
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document.write( "The feature of this fund is that it makes outpayments at the beginning of each quarter,\r\n" );
document.write( "while compounding are made at the end of each quarter.\r\n" );
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document.write( "For such a fund, the formula connecting the starting value, the periodical regular \r\n" );
document.write( "outpayment value, the number of payments and the rate of compounding is \r\n" );
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document.write( "    A = \"W%2A%281%2Br%2Fm%29%2A%28%281+-+%281%2Br%2Fm%29%5E%28-n%29%29%2F%28%28r%2Fm%29%29%29\",    (1)\r\n" );
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document.write( "where A is the starting amount, W is the regular quarterly outpayment amount, \r\n" );
document.write( "r is the annual compounding rate, m is the number of outpayments per year (m= 4 in this problem), \r\n" );
document.write( "n is the total number of outpayments/compounding (the number of quarters, in this problem),\r\n" );
document.write( "\"r%2Fm\"  is the effective rate of compounding per the quarter (3 months) period.\r\n" );
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document.write( "With the given data, formula (1) takes the form\r\n" );
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document.write( "    81500 = .    (2)\r\n" );
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document.write( "The unknown in this equation is 'n'.\r\n" );
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document.write( "To find 'n', simplify equation (2) step by step\r\n" );
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document.write( "    \"%2881500%2F%282430%2A%281%2B0.065%2F4%29%29%29%2A%280.065%2F4%29\"  = \"1+-+%281%2B0.065%2F4%29%5E%28-n%29\"\r\n" );
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document.write( "    0.536295486 = \"1+-+%281%2B0.065%2F4%29%5E%28-n%29\"\r\n" );
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document.write( "    \"%281%2B0.065%2F4%29%5E%28-n%29\" = 1 - 0.536295486\r\n" );
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document.write( "    \"1%2F%281%2B0.065%2F4%29%5En\" = 0.463704514\r\n" );
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document.write( "    \"%281%2B0.065%2F4%29%5En\" = 1/0.463704514\r\n" );
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document.write( "    \"%281%2B0.065%2F4%29%5En\" = 2.156545754\r\n" );
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document.write( "At this point, take logarithm of both sides\r\n" );
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document.write( "    n*log(1+0.065/4) = log(2.156545754)\r\n" );
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document.write( "Express n and then calculate its value\r\n" );
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document.write( "    n = \"log%28%282.156545754%29%29%2Flog%28%281%2B0.065%2F4%29%29\" = 47.6760064\r\n" );
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document.write( "ANSWER.  The number of quarters is about 47.676, and the number of years is close to 12.\r\n" );
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\n" ); document.write( "\n" ); document.write( "Solved.\r
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\n" ); document.write( "\n" ); document.write( "After completing calculations, I think that the problem is posed in a bad way.\r
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\n" ); document.write( "\n" ); document.write( "Had the problem be posed correctly, the final number of quarters would be VERY close to an integer number.\r
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\n" ); document.write( "\n" ); document.write( "But in any case, the logic of solution and the steps should be similar to that shown in this my post.\r
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