Question

Which is the better buy?

2-pint bottle of bleach for $1.86
2-gallon bottle of bleach for $10.56

Answer 1

gallon bottle

Explanation:

There are 8 pints in a gallon, so 8 of the 2-pint bottles would be equivalent to 2 gallons. The cost of those would be ...

8 × $1.86 = $14.88

This is greater than the $10.56 cost of a 2-gallon bottle, so the 2-gallon bottle offers a better buy for an equivalent quantity.

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Additional comment

You could compare unit rates in terms of any of cost per ounce, cost per pint, cost per quart, cost per gallon. All that is needed is the cost for an equivalent quantity, or the quantity for an equivalent cost.

Or, one can look at cost and quantity ratios. The cost ratio is 10.56/1.86 ≈ 5.68; the quantity ratio is (16 pints)/(2 pints) = 8. The gallon size gives 8 > 5.7 times the product for 5.7 times the cost, so it is the better buy.