2¾=11/4 and 2⅜=19/8.
The ratio of the radii or diameters=(11/4)/(19/8)=(11/4)(8/19)=(8/4)(11/19)=22/19=1.16 approx, that is, the larger circle is about 16% bigger than the smaller circle. The areas of the circle, however, have a different ratio: (22/19)2=1.34, that is, the larger circle is about 34% bigger than the other circle.