At clock times 19.4, 29.1, 38.8 and 48.5 sec, we observe water depths of 29.8, 17.9, 9.7 and 5.3 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 19.4 and 29.1 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) - -1.65, 5 f(x) and 5 f(x- .75) + -1.65. Quickly sketch each graph.