document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1097227>Question 1097227</A>: <I><SPAN STYLE=\"word-break: break-all;\"> The annual interest rate on a credit card is 12.99%.if the minimum of $20 is made each month , how many months will it take to pay off an unpaid balance of $910.61? Assume that no purchases are made with the credit card. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #711626 by </B><A HREF=/tutors/aboutme.mpl?userid=jorel1380><B>jorel1380(3719)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=jorel1380><IMG SRC=http://www.algebra.com/images/aboutme-small.gif BORDER=0 alt=\"About Me\" VALIGN=MIDDLE></A>&nbsp;<IMG SRC=http://www.algebra.com/cgi-bin/show-face.mpl?user=jorel1380><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=711626\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Let the monthly interest rate be r and the principal be p, the <BR>\n" );
document.write( "monthly payment be x, and n be the number of months to pay the debt off. Then p = x*(1 - (1+r)^-n)/r is the formula you need in order to determine the number of months you need. In this case, the monthly interest rate is 12.99%/12, or 0.010825. So:<BR>\n" );
document.write( "910.61=20*(1-(1+0.010825)^-n)/0.010825<BR>\n" );
document.write( "0.4928676625=1-(1.010815)^-n<BR>\n" );
document.write( "1.010815^-n=0.5071323375 <BR>\n" );
document.write( "ln 1.010815^-n=ln 0.5071323375<BR>\n" );
document.write( "-n ln 1.010815=ln 0.5071323375<BR>\n" );
document.write( "n=63.12 months<BR>\n" );
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