At clock time t = 13 sec the depth of water in a container is 64 cm, while at clock time t = 35 sec the depth is 26 cm. Plot the corresponding points on a graph of depth vs. clock time and determine the slope of the straight line segment connecting these points. Explain why this slope represents the average rate at which the water depth changes over this time interval.

For the quadratic function y = f(t) = .02 t² + -2.69 t + 96, determine the average rate of change of y with respect to t, between clock times t = 35 and t = 40.