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Sub 505 Level|   Geometry|      
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Bunuel
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If the radius of a cylinder is doubled and so is the height, what is 19 Jun 2016, 10:49
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A
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If the radius of a cylinder is doubled and so is the height, what is the new volume of the cylinder divided by the old one?

A. 8.
B. 2.
C. 6.
D. 4.
E. 10.
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A
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If the radius of a cylinder is doubled and so is the height, what is 19 Jun 2016, 13:01
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let the radius be r and the the height be h.
New radius = 2r and height = 2h.

Area (new) : Area(old) = \(pi*(2r)^2*2h/pi*r^2*h\) = 8:1. Hence the answer is A.
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If the radius of a cylinder is doubled and so is the height, what is 20 Jun 2016, 03:18
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let v and v' be the original and the changed volume
now
v=pir^2h
v'=pi(2r)^2(2h)
v'=8v
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If the radius of a cylinder is doubled and so is the height, what is 20 Jun 2016, 04:00
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A,

Doubling of radius is 2r and heaight is 2h

new volume = pi*(2r)^2*2h = 8*pi*h*r^2
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If the radius of a cylinder is doubled and so is the height, what is 09 Dec 2016, 10:30
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Volume of the cylinder = \(\pi\) \(r^2\)h
if the radius is doubled then new radius would be 2r
height is doubled so the new height is 2h
new volume = \(\pi\) * \((2r)^2\)*2h = 8 \(\pi\)\(r^2\)h = 8 * original volume of the cylinder
Correct Answer - A
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If the radius of a cylinder is doubled and so is the height, what is 12 Dec 2016, 18:09
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Bunuel
If the radius of a cylinder is doubled and so is the height, what is the new volume of the cylinder divided by the old one?

A. 8.
B. 2.
C. 6.
D. 4.
E. 10.

We are give that both the radius and height of a cylinder are doubled. If we let r = radius of the cylinder and h = height of the cylinder, then the original volume of the cylinder is:

V(old) = π(r^2)h

Since the radius and height are doubled, the new volume is:

V(new) = π(2r)^2 x (2h) = π(4r^2)(2h) = 8π(r^2)h

Thus, new volume/old volume = [8π(r^2)h]/[π(r^2)h] = 8.

Answer: A
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