Circumfrence with a Twist

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Marisa: Junior | Next Rank: 30 Posts; Posts: 25; Joined: Sat Feb 28, 2009 3:50 pm

by Marisa » Fri Mar 06, 2009 6:43 am

Square S is inscribed in Circle Y which has a perimeter of 24. What is the circumference of T

IMO seems pretty straightforward:
(2)(Pi)(3) = 18.76

but the OA seems strange:

6(square root 2Pi)

Why is it the square root of 2Pi? and why is the diameter instead of the radius?

Thank you.

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Source: Beat The GMAT — Problem Solving | Fri Mar 06, 2009 6:43 am

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Re: Circumfrence with a Twist

by Brent@GMATPrepNow » Fri Mar 06, 2009 10:32 am

Marisa wrote:Square S is inscribed in Circle Y which has a perimeter of 24. What is the circumference of T

IMO seems pretty straightforward:
(2)(Pi)(3) = 18.76
but the OA seems strange:
6(square root 2Pi)
Why is it the square root of 2Pi? and why is the diameter instead of the radius?
Thank you.

You have solved for the circumference of a circle inscribed in a square (and your answer is correct!). But the question says that the square is inscribed in a circle.
By the way, I'm assuming that it is the square (S) with perimeter 24 (the wording is a little ambiguous and there is no T)

Brent Hanneson - Creator of GMATPrepNow.com

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Marisa: Junior | Next Rank: 30 Posts; Posts: 25; Joined: Sat Feb 28, 2009 3:50 pm

by Marisa » Fri Mar 06, 2009 10:56 am

Thank you. Circle T is the only circle. (I guess I shouldn't post at 6am :/ )

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