with the interval

a. Find the body's displacement and average velocity for the given time interval.

Is this all thats needed on this part or do I need to do to find the average velocity?

b. Find the body's speed and acceleration at the endpoints of the interval.

is positive because speed is always absolute value

c. When, if ever, during the interval does the body change direction.

Use the Velocity equation for this I believe and when I plug in values between the interval, the output (v) is never changed into a positive number so can I conclude it does not change direction?