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# D01-33

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Intern
Joined: 10 Feb 2017
Posts: 41
Location: India
GMAT 1: 680 Q50 V30
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20 Mar 2017, 22:54
as per question the diameter of inscribed circle should be pi not of semi circle.
the first line of the question clearly talks about the inscibed circle where it is given 'it is inscibed in a semi circle with diameter pi and is shown below'.

i think question fails to clear this out and hence the answer can vary.
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Joined: 02 Sep 2009
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21 Mar 2017, 04:21
smanujahrc wrote:
as per question the diameter of inscribed circle should be pi not of semi circle.
the first line of the question clearly talks about the inscibed circle where it is given 'it is inscibed in a semi circle with diameter pi and is shown below'.

i think question fails to clear this out and hence the answer can vary.

I think it's clear from the stem that $$\pi$$ is diameter of semicircle.
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15 Apr 2017, 14:47
Bunuel wrote:
Since the radius of the big circle ($$\frac{\pi}{2}$$) is twice the radius of the inscribed circle ($$\frac{\pi}{4}$$) then its area is 4 times greater than the area of the inscribed circle (because in the area formula the radius is squared.

Bunuel wrote:
Thus the area of the semicircle is $$\frac{4}{2}=2$$ times greater than the area of the inscribed circle

Took me a while but I finally understand this. I originally solved this algebraically but that takes too long. It's better to use the area ratio information.

(Radius Big Circle/ Radius Inner Circle) = (pi/2) / (pi/4) = 2/1

(Area Big Circle/ Area Inner Circle) = (2/1)^2 = 4/1

(Area Semicircle / Area Inner Circle) = 4/1 * 1/2 = 2/1 <-- answer
Intern
Joined: 26 Dec 2014
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24 Aug 2017, 05:49
Which circle's diameter is pi? It is confusing and not even shown in the figure.
Intern
Joined: 03 Jun 2017
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Location: United Kingdom
GMAT 1: 610 Q47 V27
GMAT 2: 700 Q49 V34
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29 Dec 2017, 07:44
I think this is a high-quality question and I agree with explanation.
Intern
Joined: 17 Jun 2017
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05 Jan 2018, 01:43
Ansari1 wrote:
Radius of semicircle is pi/2
Radius of circle is pi/4.

Then area of semicircle is pi cube/8. And area of circle is pi cube/32.

The question is ratio between area of semicircle to area not covered by circle.

Area not covered is pi cube/8 minus pi cube/32.

That is 3 pi cube/32.

Atlast, ratio = (pi cube/8) / (3 pi cube/32)
= 4/3

Then answer should be 4:3 !?

Whether my approach to this is wrong? Correct me, if is it so..
Ansari1 wrote:
Radius of semicircle is pi/2
Radius of circle is pi/4.

Then area of semicircle is pi cube/8. And area of circle is pi cube/32.

The question is ratio between area of semicircle to area not covered by circle.

Area not covered is pi cube/8 minus pi cube/32.

That is 3 pi cube/32.

Atlast, ratio = (pi cube/8) / (3 pi cube/32)
= 4/3

Then answer should be 4:3 !?

Whether my approach to this is wrong? Correct me, if is it so..
Actually even I tried the same method to get to the answer as 4:3 but whats wrong with my assumption is ..I multiplied the area of the semi-circle into 2 .. which shouldn't be the case when we are working only with the area of the circle ..
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Joined: 13 Apr 2018
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14 Apr 2018, 23:17
pi3/4/3pi3/16 = 4:3
Intern
Joined: 17 Apr 2018
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GMAT 1: 640 Q42 V35
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05 Aug 2018, 07:10
I think this is a poor-quality question and I agree with explanation. The question should be clear as to which circles diameter is pie to avoid confusion.
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05 Aug 2018, 07:15
imran1994 wrote:
I think this is a poor-quality question and I agree with explanation. The question should be clear as to which circles diameter is pie to avoid confusion.

It's not ambiguous at all. Grammatically as well as mathematically all is correct there.
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18 Oct 2018, 02:16
I think this is a high-quality question and I agree with explanation.
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Joined: 17 Sep 2013
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23 Jul 2019, 08:53
For anyone getting an answer of 4:3 , it is because they are taking the area of the "whole" big circle. We should use half that "big" circle, not all of it.
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22 Sep 2019, 23:10
I think this is a high-quality question and I agree with explanation.
Intern
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22 Sep 2019, 23:33
Very nicely explained !!
Re D01-33   [#permalink] 22 Sep 2019, 23:33

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