If f(x) = x², what are the vertex and the three basic points of the graphs of f(x- .75), f(x) - .35, 5 f(x) and 5 f(x- .75) + .35. Quickly sketch each graph.

At clock times 54.8, 82.2, 109.6 and 137 sec, we observe water depths of -59, -95.4, -116.8 and -123.3 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 54.8 and 82.2 sec represents the average rate at which depth changes during this time interval.