Question

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?

Answer 1

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?

Answer 2

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

Answer 3

r u there?

Answer 4

yes

Answer 5

ok, you need any more help?

Answer 6

how did you do your simplifying? My book got 1.89

Answer 7

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

Answer 8

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

Answer 9

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

hope thats clear