Given,
Distnace covered by the falling body in t seconds, d=16t²
the total time duration Δt=3.2-2=0.2 s
The average velocity is given by the ratio of the total distance to the time duration.
Thus the average velocity of the given body over the given time interval is given by,

On substituting the known values in the above equation,

Thus the average velocity of the given object is in the given period is 3.2 ft/s.