Satellite X and Y Orbital Period - Answer B: 1.4x10^6s

[Inertialforce]

Homework Statement

Two satellites, X and Y, are placed in orbit around a planet. Satellite X has period of revolution of 3.6x10^5s and an orbital radius of 7.5x10^8m. If the orbital radius of satellite Y is 3.0x10^9m, what is the orbital period?

A) 9.1x10^5s
B) 1.4x10^6s
C) 2.9x10^6s
D) 5.2x10^7s

Homework Equations

Kepler's third law equation:
(T1/T2)^2 = (R1/R2)^2

The Attempt at a Solution

For this question what I did was use Kepler's third law and the answer I got was "B". But I was wondering is this correct because satellite X it says it has a "period of revolution of 3.6x10^5s", is this the same as "orbital period"?

 

[Pythagorean]

For this question what I did was use Kepler's third law and the answer I got was "B". But I was wondering is this correct because satellite X it says it has a "period of revolution of 3.6x10^5s", is this the same as "orbital period"?

they are one and the same.

 

[LowlyPion]

Are you sure you have the right statement of Kepler's 3rd Law?

Isn't it P² ∝ R³ ?

http://en.wikipedia.org/wiki/Kepler's_laws_of_planetary_motion#Third_law