A circular cloth with a diameter of 20 inches is place on a circular tray of 24 inches. What fraction of the tray suface is not covered by the cloth?
A) 1/6
B) 1/5
C) 11/36
D) 15/36
E) 5/6
Target Test Prep is 20% off right now!
Use code FLASH20
Available with Beat the GMAT members only code
MORE DETAILS
Gmat Prep: circular cloth
This topic has expert replies
Rtray = 1/2(24) = 12
Rcloth = 1/2(20) = 10
We need to find:
(S tray - S cloth)/S tray
= (TT Rtray^2 - TT Rcloth^2) / TT Rtray^2 (divide TT for both sides)
= (Rtray^2 - Rcloth^2) / Rtray^2
= (12^2 - 10^2)/ 12^2
= 44/144
= 11/36
As is C
Rcloth = 1/2(20) = 10
We need to find:
(S tray - S cloth)/S tray
= (TT Rtray^2 - TT Rcloth^2) / TT Rtray^2 (divide TT for both sides)
= (Rtray^2 - Rcloth^2) / Rtray^2
= (12^2 - 10^2)/ 12^2
= 44/144
= 11/36
As is C
