BTGmoderatorLU wrote:Source: GMAT Prep

A circular cloth with a diameter of 20 inches is placed on a circular tray with a diameter of 24 inches. What fraction of the tray's surface is NOT covered by the cloth?

A. 1/6
B. 1/5
C. 11/36
D. 25/36
E. 5/6

The OA is C

Area of the tray = π/4*24^2;
Area of the cloth = π/4*20^2

=> Area NOT covered by the cloth = π/4*24^2 - π/4*20^2 = 44π

Fraction of the tray's surface is NOT covered by the cloth = Area NOT covered by the cloth / Area of the tray = 44Ï€ / (Ï€/4*24^2) = 11/36

The correct answer: C

Hope this helps!

-Jay
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BTGmoderatorLU wrote:Source: GMAT Prep

A circular cloth with a diameter of 20 inches is placed on a circular tray with a diameter of 24 inches. What fraction of the tray's surface is NOT covered by the cloth?

A. 1/6
B. 1/5
C. 11/36
D. 25/36
E. 5/6

The OA is C

The area of the cloth is π x 10^2 = 100π, and the area of the tray is π x 12^2 = 144π. Therefore, 100π/144π = 100/144 = 25/36 of the tray's surface is covered by the cloth. In other words, 11/36 of the tray's surface is NOT covered by the cloth.

Answer: C