document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=824043>Question 824043</A>: <I><SPAN STYLE=\"word-break: break-all;\"> I need mire detail solution (and explanation what formulas should be used):\r<BR>\n" );
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document.write( "A Nintendo DS costs one hundred and twenty British pounds sterling (£120). I decide today, 17th<BR>\n" );
document.write( "April 2013, to put 10p aside. Tomorrow I’ll put 15p, the day after 20p, the day after that 25p and<BR>\n" );
document.write( "so on, increasing the amount by 5p every day. At which date will I have enough to buy the<BR>\n" );
document.write( "Nintendo?<BR>\n" );
document.write( "£1 = one pound = 100 pennies = 100p </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #496040 by </B><A HREF=/tutors/aboutme.mpl?userid=stanbon><B>stanbon(75887)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=stanbon><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/images/nopicture.jpg><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=496040\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> A Nintendo DS costs one hundred and twenty British pounds sterling (£120). I decide today, 17th April 2013, to put 10p aside. Tomorrow I’ll put 15p, the day after 20p, the day after that 25p and<BR>\n" );
document.write( "so on, increasing the amount by 5p every day. At which date will I have enough to buy the<BR>\n" );
document.write( "Nintendo?<BR>\n" );
document.write( "£1 = one pound = 100 pennies = 100p<BR>\n" );
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document.write( "Series: 10 + 15 + 20 + 25 + ...<BR>\n" );
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document.write( "Arithmetic Series with a = 10 and d = 5<BR>\n" );
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document.write( "Formula: S(n) = (n/2)(A + L)<BR>\n" );
document.write( "L = A + (n-1)d<BR>\n" );
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document.write( "A = 10<BR>\n" );
document.write( "d = 5<BR>\n" );
document.write( "S(n) >= 120<BR>\n" );
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document.write( "120 =< (n/2)(10+L)<BR>\n" );
document.write( "240 =< n(10+(A+(n-1)5)<BR>\n" );
document.write( "240 =< n(10 + 10+(n-1)5)<BR>\n" );
document.write( "240 =< n(20 + 5n-5)<BR>\n" );
document.write( "240 =< n(15 + 5n)<BR>\n" );
document.write( "48 =< n(3+n)<BR>\n" );
document.write( "n^2 + 3n - 48 >= 0<BR>\n" );
document.write( "n = >= 6<BR>\n" );
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document.write( "Answer:: 17th + 6 = 23rd<BR>\n" );
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document.write( "Cheers,<BR>\n" );
document.write( "Stan H.\r<BR>\n" );
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document.write( " </SPAN>\n" );
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