Except that there were 4 triangles cut from the 4 7/8" square. So, if you assume you loose two 1/4" seams that makes it 4 3/8 on each side.
4.375 X 4.375 = 19.141
19.141 + 19.141 = 38.282
Square Root is 6.18 which is the diagonal and is bisected, so each HST would be trimmed down a bit to 3"
If you sew four 3" squares together, your block will wind up 5" finished.
So, are you thoroughly confused??????? ;-)