document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=675607>Question 675607</A>: <I><SPAN STYLE=\"word-break: break-all;\"> http://www.algebra.com/algebra/homework/Probability-and-statistics/Probability-and-statistics.faq.question.673004.html\r<BR>\n" );
document.write( "\n" );
document.write( "can someone please explain this question? what do the C's mean in the first two lines?\r<BR>\n" );
document.write( "\n" );
document.write( "thanks. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #419955 by </B><A HREF=/tutors/aboutme.mpl?userid=KMST><B>KMST(5364)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=KMST><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=KMST><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=419955\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> The C's are part of a symbol that means combinations.<BR>\n" );
document.write( "Unfortunately different names and symbols are used in different textbooks.<BR>\n" );
document.write( "To make matters worse, the symbol is hard to render, meaning that what you would write with pencil and paper may be impossible to type.<BR>\n" );
document.write( "\"10C2\" meant the number of combinations of 10 taken 2 at a time,<BR>\n" );
document.write( "meaning the number of sets of 2 girls that could be made from the 10 girls in the class.<BR>\n" );
document.write( "That was <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=10%2A9%2F2=45 ALIGN=MIDDLE  ALT=\"10%2A9%2F2=45\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "\"(10+x)C2\" meant the number of combinations of 10+x taken 2 at a time,<BR>\n" );
document.write( "meaning the number of sets of students that could be made from the 10 girls plus x boys in the class.<BR>\n" );
document.write( "That was calculated as <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=%2810%2Bx%29%289%2Bx%29%2F2 ALIGN=MIDDLE  ALT=\"%2810%2Bx%29%289%2Bx%29%2F2\"   DISABLED_style= \"max-width:90%; height:auto;\" >.<BR>\n" );
document.write( "Then, the ratio of all the number of possible sets of 2 girls,<BR>\n" );
document.write( "divided by number of all possible sets of 2 pupils,<BR>\n" );
document.write( "was set as equal to the probability of having 2 girls as the set of 2 pupils selected at random: 0.15.<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=0.15 ALIGN=MIDDLE  ALT=\"0.15\"   DISABLED_style= \"max-width:90%; height:auto;\" >=<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=45%2F%28%2810%2Bx%29%289%2Bx%29%2F2%29 ALIGN=MIDDLE  ALT=\"45%2F%28%2810%2Bx%29%289%2Bx%29%2F2%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > --> <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=0.15=+45%2A%282%2F%28%2810%2Bx%29%289%2Bx%29%29%29 ALIGN=MIDDLE  ALT=\"0.15=+45%2A%282%2F%28%2810%2Bx%29%289%2Bx%29%29%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > --> <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=0.15=+90%2F%28%2810%2Bx%29%289%2Bx%29%29 ALIGN=MIDDLE  ALT=\"0.15=+90%2F%28%2810%2Bx%29%289%2Bx%29%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > --> <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=15%2F100=+90%2F%28%2810%2Bx%29%289%2Bx%29%29 ALIGN=MIDDLE  ALT=\"15%2F100=+90%2F%28%2810%2Bx%29%289%2Bx%29%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "Then, dividing both sides of the equal sign by <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=15 ALIGN=MIDDLE  ALT=\"15\"   DISABLED_style= \"max-width:90%; height:auto;\" >,<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=15%2F100=+90%2F%28%2810%2Bx%29%289%2Bx%29%29 ALIGN=MIDDLE  ALT=\"15%2F100=+90%2F%28%2810%2Bx%29%289%2Bx%29%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > --> <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=1%2F100=+6%2F%28%2810%2Bx%29%289%2Bx%29%29 ALIGN=MIDDLE  ALT=\"1%2F100=+6%2F%28%2810%2Bx%29%289%2Bx%29%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "And cross-multiplying, or going through a couple of dividing/multiplying  both sides of the equal sign by the same number,<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=1%2F100=+6%2F%28%2810%2Bx%29%289%2Bx%29%29 ALIGN=MIDDLE  ALT=\"1%2F100=+6%2F%28%2810%2Bx%29%289%2Bx%29%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > --> <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=600=%2810%2Bx%29%289%2Bx%29 ALIGN=MIDDLE  ALT=\"600=%2810%2Bx%29%289%2Bx%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );