Solve Gravitation Problem: Find Planet Radius from 11 kg Satellite Orbit

[ChazyChazLive]

Homework Statement
A 11 kg satellite has a circular orbit with a period of 1.0 h and a radius of 4.9 × 10^6 m around a planet of unknown mass. If the magnitude of the gravitational acceleration on the surface of the planet is 41 m/s^2, what is the radius of the planet?


The attempt at a solution
I used the formula:
(4pi^2 Rs^3) / (a T^2) = Rp^2


I'm on my last try.
I got 177000000 and then 935000.
I know the formula is right for sure.
I'm not sure what's going on with my calculations. It's basic algebra, easy stuff, but I'm making some mistake... >.>

 

[Dweirdo]

What You wrote seems right...
What did You plug for T?i hope 3600sec
i got 2956411 meters
approx:
3*10^6

 

[Cyosis]

The first answer you got was because you didn't square the time. I am unsure how you got to the second answer, however I do get the same answer as Dweirdo.

 

[ChazyChazLive]

Okay I don't know how I got that second one either.
I kept plugging in the numbers and got that second answer.
For some reason, after I read Dweirdo's post, I plugged it in again and this time it worked.
Don't know what I did back then but thank you very much!