Question

The radius of sphere A is twice that of a sphere B. Find the ratio among their surface areas and the ratio among their volumes.

Answer 1

if the ratio of a 1 dimensional measurement is ,
a:b
(the radius is a 1 dimensional measurement
then the ration of the 2 dimensional
measurements surface area) is just,    
${a}^{2} + {b}^{2}$

and the ratio of the 3 dimensional measurement (volume) is just,  
${a}^{3} + {b}^{3}$

so if ratio of radius is 1:2

then ratio of SA is  1:4

and ratio of Volume is 1:8

hope this help.........