The diameter of the moon is approximately one fourth of the diameter of the earth. Find the ratio of their surface areas
Let the diameter of earth be d. Therefore, the diameter of moon will be
Radius (Earth) = 
Radius (Moon) = 
* 
= 
Surface Area of moon = 
(
)2
Surface Area of Earth = 
(
)2
Ratio = 
= 
= 
20