document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1176443>Question 1176443</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Hi<BR>\n" );
document.write( "In a class of 40 the average score was 70.25. The average scores for boys and girls were 68 and 73 respectively. How many boys were in the class. <BR>\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 #803369 by </B><A HREF=/tutors/aboutme.mpl?userid=greenestamps><B>greenestamps(13200)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=greenestamps><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=greenestamps><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=803369\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> <br><BR>\n" );
document.write( "The other tutor has provided a good solution using the standard formal algebraic method for solving problems like this.<br><BR>\n" );
document.write( "This, and a large number of other types of problems, can be seen as a weighted average problem, or a mixture problem.  Problems like that can be solved by seeing where the weighted average lies between the two given averages.<br><BR>\n" );
document.write( "Consider the overall (weighted) average and the averages of the boys and girls on a number line: 68, 70.25, and 73.<br><BR>\n" );
document.write( "With simple arithmetic, determine that the class average lies 2.25/5 = 9/20 of the way from 68 to 73.<br><BR>\n" );
document.write( "That means 9/20 of the students in the class are girls.<br><BR>\n" );
document.write( "9/20 of 40 is 18, so there are 18 girls in the class; that means 22 boys.<br><BR>\n" );
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