Geometry GMAT Prep question- Experts plz confirm ans.

[anks17]

GMAT Experts,

Shouldn't the answer for attached question be pi*S(2R + S)? Can you please confirm the same.Thanks.

[eagleeye]

GMAT Experts,

Shouldn't the answer for attached question be pi*S(2R + S)? Can you please confirm the same.Thanks.

Radius of medallion = r
Radius of glass interior = r-s

Area = pi * (r^2 -(r-s)^2) = pi * ( (r+r-s)(r-r+s)) = pi * (2r-s)(s) . ( using a^2-b^2 = (a+b)(a-b) )

E is correct.

[anks17]

I solved as below. What is wrong ?

Radius of Outer circle = R+S and Radious of Inner Circle = R
(as per diagram and question)

Area of Outer Circle = Pi * (R+S)^2
Area of Inner Circle - Pi * R^2
Area of Shaded Portion or Metal Frame = Pi [(R+S)^2 - (R^2)]= Pi(S^2 + 2S)

[anks17]

Eagleeye, got it, It seems R is radius of Outer Circle and I thought that it is radius of inner circle and hence a different answer, Thanks for your quick replies