Problem Solving

AAPL wrote:A spaceship that is traveling 3,600 kilometers per hour can make a circular orbit around a spherical planet in 4 minutes. Approximately how far is the spaceship from the center of the planet?

A. 24,000 kilometers
B. 1,200 kilometers
C. 240 kilometers
D. 120 kilometers
E. 40 kilometers

The OA is E.

I don't have clear this PS question, I appreciate if any expert explain it for me. I solve it of the following way,

I need to determine the distance that the spaceship cover around of the planet, right? Then the distance will be,
$$D=Speed\ \cdot Time=3,600\cdot\left(\frac{4}{60}\right)=240\ kilometers$$
Then I know that the orbit will be spherical, that's mean that I can say that the spaceship is traveling over a circumference with lenght 240 kilometers, right?



Therefore, I need to determine the radius of this circumference and it will be,
$$L_{circumference}=2\cdot\pi\cdot r\ ,\ then\ r=\frac{L}{2\cdot\pi}$$
$$Finally,\ r=\frac{240}{2\cdot\pi}=38.19\approx40\ kilometers$$
Thank you so much.

Brent@GMATPrepNow wrote:

[email protected] wrote:Is there a way to know what level these question's' fall into on BEAT THE GMAT, sorry am a new user seeking to know more

No, BTG doesn't have that functionality (yet).
I'd say the question falls in the 500-600 range

Cheers,
Brent