Answer:
The bowlling shell's thickness is 2.7"
Explanation:
The geometry of the problem is based in the differences between the volumes in a small sphere and a spherical shell, both objects compose the total volume of the bowling ball.
The equivalence in the total ball height and the equivalent height in the fluid (in this case water displacement of half ball volume) is used for calculating the forces state that allows the static balance of the ball and the flotation force from the fluid (Archimedes principle).
In the image is showed the formulation.
