document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1199078>Question 1199078</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A circular pool measures 10 feet across. One cubic yard of concrete is to be used to create a circular border of uniform width around the pool. If the border is to have a depth of 3 inches, how wide will the border be? Use 3.14 to approximate pi. Express your solution rounded to two decimal places. (1 cubic yard = 27 cubic feet)\r<BR>\n" );
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document.write( "I don't know how to do this problem. I simply followed a sample found on this website.\r<BR>\n" );
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document.write( "Let d = depth of the border\r<BR>\n" );
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document.write( "Let w = width of border to be found\r<BR>\n" );
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document.write( "Let V = volume of pool\r<BR>\n" );
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document.write( "Let r = radius of pool\r<BR>\n" );
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document.write( "V = d•pi(w + r)^2 - pi (25•d) = 27\r<BR>\n" );
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document.write( "V = 3•pi(w + 5)^2 - pi(25•3) = 27\r<BR>\n" );
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document.write( "V = 3•pi(w + 5)^2 - 75•pi = 27\r<BR>\n" );
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document.write( "Subtract 27 on both sides. \r<BR>\n" );
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document.write( "Set V = 0 and solve for w. \r<BR>\n" );
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document.write( "0 = 3•pi(w + 5)^2 - 75•pi - 27 \r<BR>\n" );
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document.write( "After solving for w, I get two approximations: \r<BR>\n" );
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document.write( "-10.27871 and 0.278711\r<BR>\n" );
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document.write( "Of course, I must reject the negative value for w because distance must be positive. <BR>\n" );
document.write( "The book's answer for the width of the border is 2.71 feet wide.\r<BR>\n" );
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document.write( "What am I doing wrong?\r<BR>\n" );
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document.write( "Thank you. \r<BR>\n" );
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document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #832769 by </B><A HREF=/tutors/aboutme.mpl?userid=ikleyn><B>ikleyn(52781)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=ikleyn><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=ikleyn><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=832769\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> .\r<BR>\n" );
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document.write( "Your error is that you use wrong value for the thickness &nbsp;\" d \" &nbsp;of the circular walkway.\r<BR>\n" );
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document.write( "According to the problem, &nbsp;it is &nbsp;3 inches (sic !), &nbsp;which is &nbsp;0.25 &nbsp;of the foot.\r<BR>\n" );
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document.write( "&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;1 foot = 12 inches\r<BR>\n" );
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document.write( "So the correct value for &nbsp;d &nbsp;is &nbsp;&nbsp;d = 0.25 ft;  &nbsp;&nbsp;NOT &nbsp;&nbsp;d = 3 ft.\r<BR>\n" );
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document.write( "&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;They caught you in the trap, &nbsp;using different measurement units . . . \r<BR>\n" );
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document.write( "Happy calculations and re-calculations &nbsp;(&nbsp;!&nbsp;)\r<BR>\n" );
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