5. if the average velocity of a duck is zero in a given
time interval, what can you say about the displace-
ment of the duck for that interval?

If the average velocity of the duck is zero, it means that the duck's location at the end of the time interval was the same as at the beginning of the interval, but says nothing about the duck's motion during that time.
For instance, the duck could have waddled around in a circle 20 times; as long as it wound up at the starting point, the displacement and average velocity is zero.