Suppose you want to buy sugar. Packages of different sizes cost different amounts, but the relationship is not always proportional. That is, a bag twice as big does not usually cost twice as much. The chart shows the prices for various sizes of bags of sugar.
½ lb bag
1 lb bag
2 lb bag
5 lb bag
10 lb bag
20 lb bag
Find the rates in cost per pound. (Stores refer to this as unit pricing.)
Divide the price ($) by the pounds (lbs).
Does the unit price increase or decrease with the size of the bag?
Does the unit rate change more drastically for smaller sizes or for larger sizes?
List your unit prices in order. Then determine the amount of change between each value.
Are the changes getting larger or smaller in magnitude?