If water depths of 33, 16.5, 7.9 and 7.3 cm are observed at clock times 36.4, 54.6, 72.8 and 91 sec, then at what average rate does the depth change during each time interval?

Sketch a graph of this data set and use a sketch to explain why the slope of this graph between 54.6 and 72.8 sec represents the average rate at which depth changes during this time interval.

 If f(x) = x², give the vertex and the three basic points of the graphs of f(x--.75), f(x) - .35, .2 f(x) and .2 f(x--.75) + .35. Quickly sketch each graph.