Arithmetic Ability
Area

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Q.

A circular swimming pool is surrounded by a concrete wall 4ft wide. If the area of the concrete wall surrounding the pool is 11/25 that of the pool, then the radius of the pool is?

View Answer

Correct choice: B

Explanation:

let the radius of the pool be Rft Radius of the pool including the wall = (R+4)ft Area of the concrete wall = π[(R+4)2−R2] =π[(R+4+R)(R+4−R)] = 8π(R+2) sq feet => 8π(R+2) = 1125πR2 =>11R2 =200(R+2) Radius of the pool R = 20ft
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