document.write( "Question 1096173: You want to have $6,000 saved up for a new car in 4 years. How much should you deposit each quarter into an account paying 8% compounded quarterly? \n" ); document.write( "
Algebra.Com's Answer #710638 by jim_thompson5910(35256)\"\" \"About 
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\n" ); document.write( "We will use this formula
\n" ); document.write( "FV = P*( (1+i)^n - 1 )/i
\n" ); document.write( "where generally,
\n" ); document.write( "FV = future value of annuity
\n" ); document.write( "i = interest rate per period
\n" ); document.write( "n = number of periods\r
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\n" ); document.write( "\n" ); document.write( "Specifically we can say
\n" ); document.write( "FV = target amount of money we want four years into the future
\n" ); document.write( "i = interest rate per quarter
\n" ); document.write( "n = number of quarters\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "In this case, we are given
\n" ); document.write( "FV = 6000
\n" ); document.write( "i = (interest rate in decimal form)/(compounding frequency) = 0.08/4 = 0.02
\n" ); document.write( "n = (compounding frequency)*(number of years) = 4*4 = 16\r
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\n" ); document.write( "\n" ); document.write( "Plug FV = 6000, i = 0.02, and n = 16 into the formula. Then solve for P\r
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\n" ); document.write( "\n" ); document.write( "FV = P*( (1+i)^n - 1 )/i
\n" ); document.write( "6000 = P*( (1+0.02)^16 - 1 )/0.02
\n" ); document.write( "6000 = P*( (1.02)^16 - 1 )/0.02
\n" ); document.write( "6000 = P*(1.372786 - 1 )/0.02
\n" ); document.write( "6000 = P*(0.372786/0.02)
\n" ); document.write( "6000 = P*18.6393
\n" ); document.write( "6000 = 18.6393*P
\n" ); document.write( "18.6393*P = 6000
\n" ); document.write( "18.6393*P/18.6393 = 6000/18.6393
\n" ); document.write( "P = 321.900501
\n" ); document.write( "P = 321.91\r
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\n" ); document.write( "\n" ); document.write( "So the answer is $321.91\r
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\n" ); document.write( "\n" ); document.write( "I rounded up to the nearest penny so we could clear the hurdle. Notice how if P = 321.90, then we have FV equal to...
\n" ); document.write( "FV = P*( (1+i)^n - 1 )/i
\n" ); document.write( "FV = 321.90*( (1+0.02)^16 - 1 )/0.02
\n" ); document.write( "FV = 321.90*( (1.02)^16 - 1 )/0.02
\n" ); document.write( "FV = 321.90*(1.372786 - 1 )/0.02
\n" ); document.write( "FV = 321.90*(0.372786/0.02)
\n" ); document.write( "FV = 321.90*18.6393
\n" ); document.write( "FV = 5999.99067
\n" ); document.write( "FV = 5999.99
\n" ); document.write( "Showing that we come up 1 cent short of our goal\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "On the other hand, if we have P = 321.91, then FV is...
\n" ); document.write( "FV = P*( (1+i)^n - 1 )/i
\n" ); document.write( "FV = 321.91*( (1+0.02)^16 - 1 )/0.02
\n" ); document.write( "FV = 321.91*( (1.02)^16 - 1 )/0.02
\n" ); document.write( "FV = 321.91*(1.372786 - 1 )/0.02
\n" ); document.write( "FV = 321.91*(0.372786/0.02)
\n" ); document.write( "FV = 321.91*18.6393
\n" ); document.write( "FV = 6000.177063
\n" ); document.write( "FV = 6000.18
\n" ); document.write( "we haven't landed on the exact value of $6000 but overshot it (which is better than coming up short). So this confirms we have the correct answer of $321.91
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