If water depths of -1.9, -14.4, -21.2 and -22.3 cm are observed at clock times 26.6, 39.9, 53.2 and 66.5 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 39.9 and 53.2 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- 1.75), f(x) - 1.85, .2 f(x) and .2 f(x- 1.75) + 1.85. Quickly sketch each graph.