Interpreting Function Notation

A function $N = f (y)$ gives the number of police officers, $N,$ in a town in year $y .$ What does $f (2005) = 300$ represent?

Work it out on paper first. Then open the solution one step at a time, and stop as soon as you can finish on your own.

Solution
When we read $f (2005) = 300,$ we see that the input year is 2005. The value for the output, the number of police officers $(N),$ is 300. Remember, $N = f (y) .$ The statement $f (2005) = 300$ tells us that in the year 2005 there were 300 police officers in the town.

Your turn

The book's Try It right after this example: same idea, new numbers. Only the answer is given.

Use function notation to express the weight of a pig in pounds as a function of its age in days $d .$

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