If water depths of 10, -6.2, -16.9 and -22.2 cm are observed at clock times 21.4, 32.1, 42.8 and 53.5 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 32.1 and 42.8 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) - -.15, .5 f(x) and .5 f(x--.75) + -.15. Quickly sketch each graph.