Marla is thinking about getting a canvas tote bag to avoid using plastic bags at the grocery store. If making the canvas bag released 600 pounds of carbon dioxide, each plastic bag released 4 ounces of carbon dioxide, and Marla uses eight bags per shopping trips, how many shopping trips will she have to make before the canvas bag is the lower-carbon solution? (There are 16 ounces in a pound.)
Thoughts? Step-by-step reasoning:
First find how many ounces of carbon dioxide are released per shopping trip: 8 bags / trip * 4 oz / bag = 32 oz / trip. Then divide that amount by the number of ounces per pound to find the pounds of carbon per shopping trip: 32 oz / trip / 16 oz / pound = 2 pounds / trip. Then divide the amount of carbon used to make the tote bag by the amount of carbon saved per shopping trip to find the number of trips needed for the bag to be a better option: 600 pounds / 2 pounds / trip = 300 trips.
Thus, the answer is 300.