Answer
a) radius r=19.3cm
b) ratio of outer area to inner area of the shell = 1.0738
Work Step by Step
a) When 90% of the hollow section is taken the radius of the sphere is found by using the volume of the sphere formula. $ V= 4/3×pie× R^3 $
b) the ratio of outer and inner area of the shell is found using the area of the sphere formula. $ A= 4×pie× R^2 $
