document.write( "Question 1123820: If you start contributing to your retirement account at the age of 18 with $25 a month and you increase your contributions by $5 a month per year, how much will you be contributing a month at the age of 40?
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Algebra.Com's Answer #740192 by Theo(13342)\"\" \"About 
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you start at age 18 with $25 a month contribution to the account.
\n" ); document.write( "each year you add $5 to the monthly contribution.
\n" ); document.write( "in year 1, the monthly contribution is 25.
\n" ); document.write( "in year 2, the monthly contribution is 30.
\n" ); document.write( "in year 3, the monthly contribution is 35.
\n" ); document.write( "etc.\r
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\n" ); document.write( "\n" ); document.write( "this looks like an arithmetic progression type problem.\r
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\n" ); document.write( "\n" ); document.write( "the formula for an arithmetic progression is An = A1 + (n-1)d\r
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\n" ); document.write( "\n" ); document.write( "in this progression, A1 would be equal to 25
\n" ); document.write( "d would be equal to 5.
\n" ); document.write( "An would be 40 - 18 + 1 = 22.
\n" ); document.write( "when you are 18, it's year 1.
\n" ); document.write( "when you are 40, you add 40 - 18 = 22 to that to get year 23.\r
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\n" ); document.write( "\n" ); document.write( "the formula becomes A23 = 25 + 22 * 5 = 135.\r
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\n" ); document.write( "\n" ); document.write( "when you are 40, the monthly contribution will be 135 dollars.\r
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\n" ); document.write( "\n" ); document.write( "this can be seen in the following excel printout.\r
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