15Price per ounce, unit rate
A 12 oz bag of rice costs $3.00 and an 18 oz bag costs $4.14. Find the price per ounce of each bag. Which is the better buy?
The 12 oz bag costs $0.25 per ounce, and the 18 oz bag costs $0.23 per ounce, so the 18 oz bag is the better buy. You find this by dividing each price by its ounces: 3.00/12 = 0.25 and 4.14/18 = 0.23, then comparing the two rates.