I had to calculate by hand the case for x = 36 pi. Once I simplified the expression, I added a condition for this case. Otherwise, (I guess due to machine error) I wouldn't get it right even though I had the correct code.

If surface is 36*pi, then volume is (4/3)*pi*(sqrt(36*pi/4/pi))^3

This is math. If one answer is right, they should all be right.

Is this a roundoff question?