Hi lheiannie07,

We're told that a circular mat with diameter 20 inches is placed on a square tabletop, each of whose sides is 24 inches long. We're asked which of the following fractions is CLOSEST to the fraction of the tabletop covered by the mat.

To start, we'll need to calculate the areas of the two shapes:
Area of circular mat = (pi)(R^2) = (pi)(10^2) = 100pi = approximately 314
Area of square table = (side)^2 = (24)^2 = 576

Now we have to approximate the value of 314/576. Half of 576 would be LESS than 300. Since we're dealing with a numerator of 314, the fraction is clearly GREATER than 1/2. Relative to the other two answers though (3/4 and 5/6), that fraction really isn't close (3/4 of 576 would be pretty close to 3/4 of 600, which would make it a bit less than 450 - and 5/6 would be even greater). Thus, the answer that's closest is 1/2.

Final Answer: C

GMAT assassins aren't born, they're made,
Rich