A space shuttle orbits the earth at about 6 kilometers per second. This speed is equal to how many kilometers per hour?  Choose the correct choice from the following choices
A) 480
B) 2,880
C) 21,600
D) 28,800
E) 48,000

Rationale: seconds in 1 hours : 60 s in 1 min 60 min in 1 hr 60 * 60 = 3600 sec in 1 hr 6 * 3600 = 21,600 answer : c
Answer: C