document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1129628>Question 1129628</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Hello. I am really struggling with my averages right now and I need some help with this question. I'm a 6th grader and not really good at maths, so please try to explain it as simple as you can. So here's my question: The daily average training time of sportsmen A, B and C is 12.2 hours. The daily average training time of sportsmen A,B,C and D is 11.5 hours. What is the daily training time of sportsman D? I suppose that sportsman D's training time is lesser than the other, making the total average of A, B, C and D lower.  </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #746201 by </B><A HREF=/tutors/aboutme.mpl?userid=math_helper><B>math_helper(2461)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=math_helper><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=math_helper><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=746201\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Your reasoning is correct, D has a lower daily training time because including D brings the average time down. <br>\r<BR>\n" );
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document.write( "We can find D's time as follows:\r<BR>\n" );
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document.write( "The average of A,B,C is found by adding their times and dividing by 3:<BR>\n" );
document.write( "(A+B+C)/3 = 12.2    (eq 1)<br>\r<BR>\n" );
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document.write( "The average of A,B,C,D is found by adding their times and dividing by 4:<BR>\n" );
document.write( "(A+B+C+D)/4 = 11.5   (eq 2) <br>\r<BR>\n" );
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document.write( "In (eq 1), multiply both sides by 3:    <BR>\n" );
document.write( "3*(A+B+C)/3 = 3*12.2     <—— the left hand side will become 1*(A+B+C) or just A+B+C<BR>\n" );
document.write( "A+B+C = 36.6<br>\r<BR>\n" );
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document.write( "In (eq 2), multiply both sides by 4:    <BR>\n" );
document.write( "4*(A+B+C+D)/4 = 4*11.5<BR>\n" );
document.write( "A+B+C+D = 46 <br>\r<BR>\n" );
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document.write( "Now notice we can substitute 36.6 for \"A+B+C\" in this last equation:  <BR>\n" );
document.write( "36.6 + D = 46<br>\r<BR>\n" );
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document.write( "Finally, subtracting 36.6 from both sides:<BR>\n" );
document.write( "36.6 + D - 36.6 = 46 - 36.6<BR>\n" );
document.write( "   D = 46-36.6 <BR>\n" );
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