18. Use differentials and the graph of f to approximate a. f (1.95) (2,4) f (0,3) b . f ( 2.1 ) 19. The volume of a sphere is V = Anr3. a. Find the differential dV. b If the radius of a sphere is measured to be 20 inches with a possible error of /32 inch, use differentials to approximate the propagated error in computing the volume of the sphere. C. If the radius of the sphere is measured with an error of 12%, what is the percentage error in computing the volume of the sphere