question: The radius of a cylinder is increased by 15% and its height is decreased by 20%. Find the percentage change in the volume of the cylinder.
answer: ?????
2007-07-08 22:35:19 · 5 answers · asked by sguy 1 in Science & Mathematics ➔ Mathematics
1.15^2 * 0.8 = 1.058
(No need to calculate the volumes of both cylinders.)
2007-07-09 00:00:23 · answer #1 · answered by oregfiu 7 · 1⤊ 0⤋
If the Radius is r and the height is h then
V=Pi(r^2)h
Now if you alter it as in your question then
V=Pi[(1.15r)^2]0.8h
V=Pi(r^2)h.1.058
In other words the Volume is increased by 5.8%.
2007-07-09 06:35:36 · answer #2 · answered by Anonymous · 0⤊ 0⤋
assume intial radius is 2 and hight is 4
there intial volume is
3.14*r^2 *h
3.14*4*4=50.24
increase radius by 15% and reduce hight by 20%
100%=2
115%=2.3
100%=4
80% =3.2
therefore new volume =
3.14*r^2 *h
3.14*5.29*3.2=53.15
new volme- intial volume =
53.15-50.24=2.91
therefore%difference= (2.91/50.24)*100=5.8%
2007-07-09 06:23:41 · answer #3 · answered by Anonymous · 1⤊ 0⤋
volume=pi*(1.15r)^2*0.8h
=1.058 times initial volume
that is increased by 5.8%
2007-07-09 05:42:35 · answer #4 · answered by Friend 3 · 1⤊ 0⤋
answer is 5.8%
2007-07-09 05:50:09 · answer #5 · answered by Anonymous · 0⤊ 0⤋