Comparing unit prices involves finding and interpreting the cost for one common unit, such as dollars per ounce, item, or pound, by dividing total price by quantity and then comparing the resulting rates. The comparison may require equivalent units and decimal or fraction calculations; a lower total price or larger package is not necessarily the better value. This reasoning develops proportional understanding of rates and supports later work with ratios, percentages, and algebraic relationships.
To compare prices fairly, find the unit price for each option. A unit price tells you the cost of one unit, such as 1 ounce or 1 item.
A store sells two boxes of cereal:
Which box is the better value?
Step 1: Make sure the units match.
Both quantities are measured in ounces, so we can compare their prices per ounce.
Step 2: Find the unit price of each box.
Divide the total price by the number of ounces:
Step 3: Compare the unit prices.
Box A costs less for each ounce.
Answer: Box A is the better value, even though it has the higher total price. Always compare the unit prices, not just the package prices.
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