document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1199918>Question 1199918</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Mulch is sold by the cubic yard.  To estimate number of cu. yds. needed for a circular bed, determine sq. footage.\r<BR>\n" );
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document.write( "Sq. footage = area of circle (pi * r^2).\r<BR>\n" );
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document.write( "3.1416 * 10^2 = 314 sq. ft. (10 ft. is example). \r<BR>\n" );
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document.write( "Convert sq. ft. to cu. ft.\r<BR>\n" );
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document.write( "Depth of mulch in inches.\r<BR>\n" );
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document.write( "314 * 4 (depth wanted)  = 1256\r<BR>\n" );
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document.write( "Divide by 324:  1256 / 324 = 3.876 = 4 cu. yds.\r<BR>\n" );
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document.write( "My question:  What does the 324 signify?\r<BR>\n" );
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document.write( "Note: 324 is used also for a square or rectangular bed (after obtaining sq. footage, multiply by depth of mulch needed, and again / by 324.)\r<BR>\n" );
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document.write( "A = pi*r^2<BR>\n" );
document.write( "A = 3.14*10^2<BR>\n" );
document.write( "A = 314 sq ft is the approximate area of the circle with radius 10 ft.\r<BR>\n" );
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document.write( "The calculation 314*4 only makes sense if the second \"4\" is in feet.<BR>\n" );
document.write( "Multiplying feet with inches doesn't make sense without a conversion.<BR>\n" );
document.write( "More generally, the units need to match up when multiplying dimensions.\r<BR>\n" );
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document.write( "(314 sq ft) * (4 ft) = 1256 cubic ft is valid<BR>\n" );
document.write( "(314 sq ft) * (4 inches) = 1256 cubic ft is NOT valid\r<BR>\n" );
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document.write( "The second equation must be this instead<BR>\n" );
document.write( "314 sq ft * (4/12) ft = 104.6666667 cubic ft\r<BR>\n" );
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document.write( "Note the division by 12. So we have a 12 in the denominator.<BR>\n" );
document.write( "4 inches = 4/12 of a foot = 1/3 of a foot\r<BR>\n" );
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document.write( "We'll also have 27 in the denominator due to the steps below<BR>\n" );
document.write( "1 yard = 3 feet<BR>\n" );
document.write( "(1 yard)^3 = (3 feet)^3<BR>\n" );
document.write( "1 cubic yard = 27 cubic feet\r<BR>\n" );
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document.write( "Therefore 12*27 = 324 is in the denominator to help correct for the error in the equation 314 sq ft * 4 inches = 1256 cubic ft; and to convert from cubic feet to cubic yards.<BR>\n" );
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