How do step functions apply to postage rates. Graph the function that represents a letter that cost 49 cents . Why is a step function used for this situation while gas millage as you drive to the post office cant be represented with a step function.

A step function is one that does not have a constant slope. If you wanted to graph number or letters versus cost you would have data points at (1 letter, 49cents) and (2 letters, 98 cents). But you could not connect these points because it would appear as if you could sent 1.5 letters for 73.5 cents which is not true. Now lets look at gas millage. Since gas is used continuously as you drive it will have a constant slope. For example if you get 10 miles per gallon of gas. Driving 20 miles would use 2 gallons or driving 5 miles would use .5 gallons.

Hope this makes sense. The bottom line is you but stamps in increments of 49 cents. You cant buy one and a half stamps.