Question

what is the total surface area of a hollow sphere?

Answer 1

 surface area of a hemisphere is:    2πr2 This hemisphere is hollow.  It has a total surface area of:      outer surface area       +      inner surface area        +      area of ring           2π(1.25)2              +       2π(1.86/2)2          +   (  π(1.25)2  -  π(1.86/2)2  )           3π(1.25)2       +     π(1.86/2)2            3π(1.25)2    +  π(0.93)2          14.71875    +   2.715786                    17.43454                     17.43 cm2     (rounded)

Answer 2

4*$\pi$*r^2 is the surface area of a hollow  sphere