sandy wrote:
If a right circular cylinder’s radius is halved and its height doubled, by what percent will the volume increase or decrease?
(A) 50% decrease
(B) 0%
(C) 25% increase
(D) 50% increase
(E) 100% increase
Volume of a circular cylinder = \(\pi\) * \({radius}^2\) *
heightnow, when the radius is reduced by 2 and height doubled, volume = \(\pi * {\frac{R}{2}}^2 * 2H\)= \(\frac{{\pi * {R}^2 * H}}{2} \), which is decreased by 50%
*****We can use some nice nos.
Let Radius = 4
Height = 2
Volume =\( \pi*4^2 * 2 = 32\pi\)
Radius is halved and height doubled, volume =\( \pi*2^2 * 4 = 16\pi\) , i.e volume decreased by
50%
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