document.write( "Question 287598: A right circular cylinder is given. If the radius is increased by 25% then the volume will stay the same if the height is increased/decreased by what percent?\r
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document.write( "(a) Increased by 64% (b) Decreased by 36% (c) Decreased by 25%
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document.write( "(d) Increased by 25% (e) None of the above \n" );
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Algebra.Com's Answer #208366 by dabanfield(803)![]() ![]() ![]() You can put this solution on YOUR website! A right circular cylinder is given. If the radius is increased by 25% then the volume will stay the same if the height is increased/decreased by what percent? \n" ); document.write( "(a) Increased by 64% (b) Decreased by 36% (c) Decreased by 25% \n" ); document.write( "(d) Increased by 25% (e) None of the above\r \n" ); document.write( "\n" ); document.write( "Let r be the original radius, h the original height and H the new increased height. Then we have:\r \n" ); document.write( "\n" ); document.write( "1.) volume of original cylinder = pi*(r^2)*h \n" ); document.write( "2.) volume of cylinder with increased radius = pi*(1.25r)^2*H\r \n" ); document.write( "\n" ); document.write( "For the volume not to change we must have:\r \n" ); document.write( "\n" ); document.write( "pi*(r^2)*h = pi*(5/4*r)^2*H \n" ); document.write( "pi*(r^2)*h = pi*25/16*r^2*H\r \n" ); document.write( "\n" ); document.write( "Divide both sides above by pi:\r \n" ); document.write( "\n" ); document.write( "r^2*h = (25/16)*r^2*H\r \n" ); document.write( "\n" ); document.write( "Divide both sides by r^2:\r \n" ); document.write( "\n" ); document.write( "h = (25/16)*H \n" ); document.write( "H = (16/25)*h \n" ); document.write( "H = .64*h\r \n" ); document.write( "\n" ); document.write( "The height must be DECREASED by .36, that is 36%.\r \n" ); document.write( "\n" ); document.write( " \n" ); document.write( " |