When an object is falling through a fluid like air it is affected by two forces: the down force of gravity and the drag force. The first one points to the ground and accelerates the object whereas the drag force points in the opposite direction and decelerates it. While the force of gravity is bigger than the drag force the velocity of de object increases. At some point the drag force increases enough to equal gravity and the velocity of the object stops increasing and reaches a maximum known as the terminal velocity.
By looking at the table you'll notice that from 0 to 5 seconds the velocity of the object increases but between 5 and 6 seconds after it began falling the velocity remains constant. This means that during this interval the force of gravity and the drag force are equal and the objects falls with its terminal velocity, 50.
AnswerThen the answer is 50 feet per second.