At a supermarket a 6 ounce bottle of salad dressing costs $1.56. A 14 ounce bottle costs $3.36. A 20 ounce bottle costs $5.60. Which bottle has the lowest cost per ounce

First, you must find the unit price of each salad dressing bottle (cost/unit).

Bottle 1:

$1.56/6oz = $0.26 per ounce

Bottle 2:

$3.36/14oz = $0.24 per ounce

Bottle 3:

$5.60/20oz = $0.28 per ounce

Therefore, Bottle 2 has the lowest cost per ounce.