Consider both Earth and Mars to be spheres. The surface area of mars is about 28% that of earth. What is the ratio of their radii?

Question

anonymous · Answer

surface area of a sphere = 4 pi r^2
if radis earth = re and of mars is rm then

4 pi rm^2            28
--------  =       ---
4 pi re^2             100
can you continue from here?

anonymous · Answer

from the above  rm^2 / re^2 = 28 / 100
so rm / re = sqrt28 / 10

anonymous · Answer

r u there?

anonymous · Answer

yes

anonymous · Answer

ok,  you need any more help?

anonymous · Answer

how did you do your simplifying? My book got 1.89

anonymous · Answer

hmmm 
sqrt28 = 5. 29 
so ratio is 0.53 to 2 d p
0h - ratio of mars to earth = 100 / 0.53 =  1 : 1.89

anonymous · Answer

or put another way the radius of the earth = 1.89 times the radius of mars

anonymous · Answer

i worked out radius of mars as fraction of the earth's

hope thats clear