document.write( "Question 1102126: a conical tank with vertex at the bottom is being filled at a rate of 4 cubic m per minute. the tank is 24 m deep and 12 m at the top. find the rate of change of the depth of the waste when the water id 8m deep \n" ); document.write( "
Algebra.Com's Answer #716765 by greenestamps(13200)\"\" \"About 
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\n" ); document.write( "You didn't specify whether the 12m is the radius or the diameter of the top of the tank. By the way you state the problem, I assume it is the full width (diameter) of the top of the tank.

\n" ); document.write( "Then the radius of the top of the tank is 6m; since the depth of the tank is 24m, the radius is 1/4 of the depth. As the tank is being filled, the volume of water forms a cone that is similar to the whole tank; so at any time the radius of the surface of the water in the tank is 1/4 the depth of the water.

\n" ); document.write( "So the volume of water when the depth is h is
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\n" ); document.write( "\"dV%2Fdt+=+%281%2F16%29%28pi%29h%5E2%28dh%2Fdt%29\"

\n" ); document.write( "\"dh%2Fdt+=+%2816%2F%28%28pi%29h%5E2%29%29%2A%28dV%2Fdt%29\"

\n" ); document.write( "We know dV/dt is 4; when the depth h is 4, dh/dt is
\n" ); document.write( "\"%28%2816%2F%28%28pi%294%5E2%29%29%2A4%29+=+4%2Fpi\"
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