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# If the diameter of circle C is 3 times the diameter of circl

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If the diameter of circle C is 3 times the diameter of circl [#permalink]  24 Jan 2017, 07:48
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Question Stats:

94% (00:50) correct 5% (01:22) wrong based on 17 sessions

If the diameter of circle C is 3 times the diameter of circle D, then the area of circle C is how many times the area of circle D ?

[Reveal] Spoiler: times greater
9

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Re: If the diameter of circle C is 3 times the diameter of circl [#permalink]  28 Jan 2017, 07:43
1
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Explanation

Supply a number for the diameter of Circle D and then find the radius and diameter of the other circle. We chose d = 2 so that we could have a radius of 1.

Compute the area of each circle:
Circle D: Area = $$\pi r^2$$ → $$\pi(1)^2$$ → $$1\pi$$
Circle C: Area = $$\pi r^2$$ → $$\pi(3)^2$$ → $$9\pi$$
The area of Circle C is 9 times as large as the area of Circle D.

Hence 9 is the correct answer.
[Reveal] Spoiler: Image
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di new.jpg [ 26.99 KiB | Viewed 18628 times ]

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Re: If the diameter of circle C is 3 times the diameter of circl   [#permalink] 28 Jan 2017, 07:43
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