A circular mat with diameter 20 inches is placed on a square tabletop, each of whose sides is 24 inches long.  Which of the following is closest to the fraction of the tabletop covered by the mat?

~$\frac{5}{12}$~

~$\frac{2}{5}$~

~$\frac{1}{2}$~

~$\frac{3}{4}$~

~$\frac{5}{6}$~