Calculate the circumference of the ball and then divide this circumference into 60 ft:
C = pi*d = pi*(8.5 in)
Then,
60 ft 12 in
-------- * --------- divided by 8.5 pi in comes out to:
1 1 ft
720 in 1
--------- * -------------- = 26.96, or about 27, complete revolutions.
1 8.5 pi in
