At clock times 19.8, 29.7, 39.6 and 49.5 sec, we observe water depths of 12.4, 1.9, -4.1 and -5.6 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 19.8 and 29.7 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- .25), f(x) - -.65, .25 f(x) and .25 f(x- .25) + -.65. Quickly sketch each graph.