Question

What is the displacement of the particle in the time interval 5 seconds to 8 seconds?

Answer 1

magnitude
     distance between position at 5 sec and position at 8 sec
and direction
     direction from position at 5 sec to position at 8 sec .

The route followed during the time interval is irrelevant.

Answer 2

If you're doing PLATO the answer is 1.5 meters.