If water depths of 27.1, 18.4, 13.2 and 11.5 cm are observed at clock times 17.4, 26.1, 34.8 and 43.5 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 26.1 and 34.8 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- .25), f(x) - 1.85, .2 f(x) and .2 f(x- .25) + 1.85. Quickly sketch each graph.