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r is the radius
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04 Feb 2018, 15:20
04 Feb 2018, 15:20
Expert Reply
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Question Stats:
68% (00:32) correct
31% (00:51) wrong based on 74 sessions
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r is the radius of the sphere S and of the circle C
Quantity A |
Quantity B |
The ratio of the surface area of sphere S to the area of the circle C |
4 |
A) Quantity A is greater.
B) Quantity B is greater.
C) The two quantities are equal.
D) The relationship cannot be determined from the information given.
Kudos for the right solution and explanation
Sherpa Prep Representative
Joined: 15 Jan 2018
Posts: 147
Given Kudos: 0
Re: r is the radius
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04 Feb 2018, 18:35
04 Feb 2018, 18:35
2
Expert Reply
Firstly, let me just remark that problems by McGraw-Hill are generally terrible. So don't take them as a very accurate gauge of how the GRE works.
For example, you DO NOT need to memorize the surface area of a sphere. But that's the only way to solve this question. On a related note, you don't need to know the volume of a sphere, surface area of a cone, or volume of a cone. Now, a real GRE question might tell you that the surface area of a sphere is 4πr^2, and then ask you to use it. But you don't need to memorize it.
So this problem can be solved by dividing the surface area of the sphere by the area of the circle, which gets us 4πr^2/πr^2. Since everything cancels out but the 4, we're left with 4 as the ratio. Thus the answer is C.
For example, you DO NOT need to memorize the surface area of a sphere. But that's the only way to solve this question. On a related note, you don't need to know the volume of a sphere, surface area of a cone, or volume of a cone. Now, a real GRE question might tell you that the surface area of a sphere is 4πr^2, and then ask you to use it. But you don't need to memorize it.
So this problem can be solved by dividing the surface area of the sphere by the area of the circle, which gets us 4πr^2/πr^2. Since everything cancels out but the 4, we're left with 4 as the ratio. Thus the answer is C.
Re: r is the radius
[#permalink]
05 Feb 2018, 02:58
05 Feb 2018, 02:58
2
SherpaPrep wrote:
Firstly, let me just remark that problems by McGraw-Hill are generally terrible. So don't take them as a very accurate gauge of how the GRE works.
.
.
Hi SherpaPrep,
Do you mean that we can totally skip Mcgraw Hill ques?
