Did it take a certain ship less than 3 hours to travel 9 kilometers?

MANHATTAN GMAT OFFICIAL SOLUTION:

Notice that the statements provide rates in meters per minute. A good first step here is to figure out how fast the ship would have to travel to cover 9 kilometers in 3 hours. Create an RTD chart, and convert kilometers to meters and hours to minutes:

180r= 9,000
r= 50

The question asks whether the ship traveled 9 kilometers in less than 3 hours. The ship must travel faster than 50 meters/min to make it in less than 3 hours. Therefore, the question is really asking, is r > 50?

(1): SUFFICIENT: If the average speed of the ship was greater than 55 meters per minute, then r > 55. Thus, r is definitely greater than 50.

(2): INSUFFICIENT: If the average speed of the ship was less than 60 meters per minute, then r < 60. This is not enough information to guarantee that r > 50.

Answer: A.