The formula of getting the surface area of the sphere is = 4πr^{2}
For surface area of a hemisphere use 2πr^{2}
To get an area of hollowed hemisphere, you need to add outer surface area, inner surface area and area of ring.
Now you get:
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 cm^{2}
^{Hope this will help!}