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

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Joined: 16 Feb 2012
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Concentration: Finance, Economics

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30 Jun 2012, 01:43
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80% (01:26) correct 20% (42:13) wrong based on 176 sessions

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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. $$729\pi$$

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30 Jun 2012, 03:33
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 $$4 \pi r^2=324\pi$$.

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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06 May 2015, 00:21
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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12 Jul 2015, 05:34
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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12 Jul 2015, 10:24
1
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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15 Apr 2017, 16:29
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Re: The volume of a sphere with radius r is 4/3*pi*r^3 &nbs [#permalink] 15 Apr 2017, 16:29
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