i need help with calculus

Question

If a ball is dropped from the top of a 120 m cliff its height h in meters after t seconds can be modelled by h(t)=120-4.9t^2

Find the average of change of height of the ball with respect to time over the intervals

A) 1s to 4s

Answer 1

Average rate of change of h(t) from t = 1 to t = 4 is:

 

  [h(4) - h(1)]/(4-1) = (41.6 - 115.1)/3 = -24.5 m/sec