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If the diameter of circle A is eight times that of circle B, what is

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Bunuel
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If the diameter of circle A is eight times that of circle B, what is [#permalink] New post   30 Oct 2018, 02:37
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If the diameter of circle A is eight times that of circle B, what is the ratio of the area of circle A to the area of circle B?

A. 4:1
B. 8:1
C. 16:1
D. 32:1
E. 64:1
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E
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If the diameter of circle A is eight times that of circle B, what is [#permalink] New post   30 Oct 2018, 03:10
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Bunuel wrote:
If the diameter of circle A is eight times that of circle B, what is the ratio of the area of circle A to the area of circle B?

A. 4:1
B. 8:1
C. 16:1
D. 32:1
E. 64:1


\(\frac{D_A}{D_B} = \frac{8}{1}\)

Ratio of Areas \(= (\frac{D_A}{D_B})^2\)

i.e. \(\frac{Area of A}{Area of B} = (\frac{8}{1})^2 =\frac{64}{1}\)

Answer: Option E
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If the diameter of circle A is eight times that of circle B, what is [#permalink] New post   31 Oct 2018, 04:50
GMATinsight wrote:
Bunuel wrote:
If the diameter of circle A is eight times that of circle B, what is the ratio of the area of circle A to the area of circle B?

A. 4:1
B. 8:1
C. 16:1
D. 32:1
E. 64:1


\(\frac{D_A}{D_B} = \frac{8}{1}\)

Ratio of Areas \(= (\frac{D_A}{D_B})^2\)

i.e. \(\frac{Area of A}{Area of B} = (\frac{8}{1})^2 =\frac{64}{1}\)

Answer: Option E


I dont know how I messed this up but radius is half of diameter. So in the area ratio why is it not taken as half?
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If the diameter of circle A is eight times that of circle B, what is [#permalink] New post   31 Oct 2018, 08:55
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MrCleantek wrote:
GMATinsight wrote:
Bunuel wrote:
If the diameter of circle A is eight times that of circle B, what is the ratio of the area of circle A to the area of circle B?

A. 4:1
B. 8:1
C. 16:1
D. 32:1
E. 64:1


\(\frac{D_A}{D_B} = \frac{8}{1}\)

Ratio of Areas \(= (\frac{D_A}{D_B})^2\)

i.e. \(\frac{Area of A}{Area of B} = (\frac{8}{1})^2 =\frac{64}{1}\)

Answer: Option E


I dont know how I messed this up but radius is half of diameter. So in the area ratio why is it not taken as half?


MrCleantek

Because ratio of Radius = Ratio of Diameters = Ratio of circumference
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Re: If the diameter of circle A is eight times that of circle B, what is [#permalink] New post   02 Nov 2018, 17:02
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Bunuel wrote:
If the diameter of circle A is eight times that of circle B, what is the ratio of the area of circle A to the area of circle B?

A. 4:1
B. 8:1
C. 16:1
D. 32:1
E. 64:1


We can let the diameter of circle A = 16 and the diameter of circle B = 2, so the radii of circles A and B are 8 and 1, respectively. Thus, the area of circle A is 64π and the area of circle B is π, yielding a ratio of:

64π/π = 64/1

Answer: E
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Re: If the diameter of circle A is eight times that of circle B, what is [#permalink] New post   29 Apr 2021, 06:02
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