Satellite x moves around earth in a circular orbit radius r. satellite y is also in a circular orbit around earth, and it completes one orbit for every eight orbits completed by satellite x. what is the orbital radius of satellite y?

 G = gravitational constant 
M = mass of the earth 
R = radius of orbit of a satellite 
r = radius of orbit of a second satellite 
v = speed of the satellite 
P = period of a satellite 
p = period of a second satellite 

Equate gravitational acceleration with centripetal acceleration 
g = G*M/R^2 = v^2/R 

Express the orbital speed in terms of the orbit circumference and period 
v = 2*pi*R/P 

And insert the expression for v into the first equation 
G*M/R = 4*PI^2*R^2/P^2 
G*M/R^3 = 4*pi^2/P^2 
R^3/P^2 = 4*pi^2/(G*M) = constant = C 

We can do the above since G and M are constants for all earth orbits 

So we can write a second equation of the same form for another satellite and equate to get: 
R^3/P^2 = r^3/p^2 
r^3 = R^3*p^2/P^2 
r = R*(p^2/P^2)^(1/3) 

For the second satellite we have p = 8*P 
r = R*(8^2)^(1/3) = R*(64)^(1/3) = 4*R

Shania is trying to determine the oldest geologic unit on this map and the reason to why is she unable to do so is that  the units are all the same age.. when there is the same age, there will be no oldest geologic unit and that i cannot be credible.