A person is moving upward in a high-rise office building using an elevator with an initial speed of 15 m/s. Three seconds later, he is still moving upward, but his speed has been reduced to 6.0 m/s.

1. What is the average acceleration of the person standing in the elevator during the 3.0 s interval?
2. If he maintains the same acceleration how much distance he will travel after 5 seconds total?
3. What is the person's speed after 5 seconds total?