A ferry traveled 1/6 of the distance between two ports in 3/7 hour. The ferry travels at a constant rate. at this rate what fraction of the distance between the two ports can the ferry travel in one hour

Answer is 7/18.

First, we determine the speed of the ferry by dividing the distance by the time it took to cover that certain distance.
speed = (1/6) / (3/7)
speed = 7/18
Then, the distance it will travel for an hour is calculated through the procedure below. 
distance = (7/18hour) x (1 hour)
distance = 7/18
Therefore, after an hour, the ferry will be able to travel 7/18 of the distance between two ports.