Whenever postage rates change, some newspaper publishes a graph like this one, which shows...

Whenever postage rates change, some newspaper publishes a graph like this one, which shows the price of a first-class stamp from 1982 to 2008:

(a) Let f be the function whose rule is

  

Find f(2000) and f(2006).

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(b) Explain why the graph in the figure is not the graph of the function f. What must be done to the figure to make it an accurate graph of the function f?