Final answer:
To calculate the cost per ounce of milk, divide the cost per gallon by 128 (the number of ounces in a gallon).
Step-by-step explanation:
To calculate the cost per ounce, we need to convert the gallon to ounces. There are 128 ounces in a gallon. Therefore, if milk costs $3.95 per gallon, the cost per ounce would be:
$3.95 / 128 ounces = $0.0308 per ounce
Therefore, milk costs approximately $0.0308 per ounce.