Product A is the better buy.
Given:
Product A = 12 ounce bottle for $1.39
Product B = 24 ounce bottle for $2.79
To know which product is a better buy, we need to get the unit cost per ounce.
Product A = $ 1.39 / 12 oz = $ 0.1158 per ounce
Product B = $ 2.79 / 24 oz = $ 0.1163 per ounce
Basically, the difference of each unit cost is very minimal. If we considered only using two decimal places, both products would cost $ 0.12 per ounce.
However, their unit costs are not limited to two decimal places only. So, the better buy is Product A which costs $0.1158 per ounce.