At clock times 24.4, 36.6, 48.8 and 61 sec, we observe water depths of -4.7, -21.7, -31.9 and -35.3 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 24.4 and 36.6 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) - -.15, .5 f(x) and .5 f(x--.75) + -.15. Quickly sketch each graph.