At clock times 13.4, 20.1, 26.8 and 33.5 sec, we observe water depths of 28, 20.9, 16 and 13.4 cm.

• At what average rate does the depth change during each time interval?

Sketch a graph of depth vs. clock time.

• Use a sketch to explain why the slope of this graph between 13.4 and 20.1 sec represents the average rate at which depth changes during this time interval.

If f(x) = x², what are the vertex and the three basic points of the graphs of f(x- .75), f(x) - 1.35, 5 f(x) and 5 f(x- .75) + 1.35. Quickly sketch each graph.