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The volume of a sphere with radius r is 4/3*pi*r^3

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The volume of a sphere with radius r is 4/3*pi*r^3 [#permalink]

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New post 30 Jun 2012, 00:43
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The volume of a sphere with radius r is \(\frac {4}{3} \pi r^3\) and the surface area is \(4 \pi r^2\). If a special ballon has a volume of \(972\pi\)cubic centimeters, what is the surface area of the ballon in square centimeters?

A. 324
B. 729
C. \(243\pi\)
D. \(324\pi\)
E. \(729\pi\)
[Reveal] Spoiler: OA

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Re: The volume of a sphere with radius 4/3*pi*r^3 [#permalink]

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New post 30 Jun 2012, 02:33
The volume of a sphere with radius r is \(\frac {4}{3} \pi r^3\) and the surface area is \(4 \pi r^2\). If a special ballon has a volume of \(972\pi\)cubic centimeters, what is the surface area of the ballon in square centimeters?

A. 324
B. 729
C. \(243\pi\)
D. \(324\pi\)
E. \(729\pi\)


Given: \(Volume=\frac {4}{3} \pi r^3=972\pi\) --> \(r=9\);

So, the surface area would be \(4 \pi r^2=324\pi\).

Answer: D.

For more on 3-D geometries check this: math-3-d-geometries-102044.html

Hope it helps.
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Re: The volume of a sphere with radius r is 4/3*pi*r^3 [#permalink]

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New post 05 May 2015, 23:21
we do not have to remember the formular for volume and surface area of a ball. is that right?

that is good
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Re: The volume of a sphere with radius r is 4/3*pi*r^3 [#permalink]

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New post 12 Jul 2015, 04:34
thangvietnam wrote:
we do not have to remember the formular for volume and surface area of a ball. is that right?

that is good


As far as I know, we do not have to remember it. Economist also supports that:

"If you find these formulas hard to remember, don't sweat it. If a sphere is tested in the GMAT, the problem always supplies the relevant formula."
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Re: The volume of a sphere with radius r is 4/3*pi*r^3 [#permalink]

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New post 12 Jul 2015, 09:24
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r^3 = 972*3/4 = 729.
so, r = 9.
Surface area = 4(pi)(9)^2 = 324 (pi). Ans (D).
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Re: The volume of a sphere with radius r is 4/3*pi*r^3 [#permalink]

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New post 15 Apr 2017, 15:29
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Re: The volume of a sphere with radius r is 4/3*pi*r^3   [#permalink] 15 Apr 2017, 15:29
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