document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=725194>Question 725194</A>: <I><SPAN STYLE=\"word-break: break-all;\"> If the ages of the students in Class XI are inA.P. with common differnce three months and the age of the youngest student is 16 years . Find the number of students in class XI , if the sum of ages of students in 861 . </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #444011 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=444011\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> If the ages of the students in Class XI are inA.P. with common differnce three months and the age of the youngest student is 16 years . Find the number of students in class XI , if the sum of ages of students in 861 .<BR>\n" );
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document.write( "a(1) = 16 years<BR>\n" );
document.write( "d = 3/12 = 1/4<BR>\n" );
document.write( "Sum = 861 years<BR>\n" );
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document.write( "a(n) = a(1) + (n-1)d<BR>\n" );
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document.write( "S(n) = (n/2)(a(1) + a(n)<BR>\n" );
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document.write( "861 = (n/2)(16 + 16+(n-1)(1/4))<BR>\n" );
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document.write( "861 = (n/2)(32 + (n-1)(1/4)<BR>\n" );
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document.write( "861 = 16n + (n^2-n)(1/8)<BR>\n" );
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document.write( "6888 = 128n + n^2-n<BR>\n" );
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document.write( "n^2 + 127n - 6888 = 0<BR>\n" );
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document.write( "n = 41<BR>\n" );
document.write( "====================<BR>\n" );
document.write( "cheers,<BR>\n" );
document.write( "Stan H.<BR>\n" );
document.write( "====================== </SPAN>\n" );
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