Gmat prep, Circle area

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Gmat prep, Circle area

by LFalken » Mon Sep 07, 2009 9:55 am
Could someone help me with this problem? It is supposed to have a figure with it, but all the figure is, is the shape of a ring.

the top side of a circular medallion made of a circular piece of colored glass is surrounded by a metal frame. If the radius of the medallion is r centimeters and the width of the metal frame is s centimeters, then in terms of s and r, what is the area of the metal frame, in square centimeters?

a) pi(r-s)^2
b) pi(r^2-s^2)
c) 2pi(r-s)
d) pi(r)(2r-s)
e) pi(s)(2r-s)

Thanks very much for anyone who has the time for this one. [/img]
LFAL

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answer

by LFalken » Mon Sep 07, 2009 9:56 am
p.s. the answer is E.... Thanks!
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by gauravgundal » Tue Sep 08, 2009 2:50 am
IMO E

The radius of circular medallion =r --- given
The width of metal frame =s --- given
The radius of the circular piece of colored glass=r-s

Area of the metal frame = Area of circular medallion - Area of circular piece of colored glass

= pi(r)^2 - (pi(r-s)^2)

= pi*s(2r-s)

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by LFalken » Tue Sep 08, 2009 9:28 am
thank you!
LFAL