If the label instructs mixing 1.5 quarts of surfactant per 100 gallons of spray, how much is needed for 45 gallons?

To determine how much surfactant is needed for 45 gallons based on the label instruction of mixing 1.5 quarts per 100 gallons, a proportionate calculation is necessary.

First, find the amount of surfactant required per gallon by dividing the total quarts by the total gallons indicated on the label. If 1.5 quarts is needed for 100 gallons, then for each gallon, the requirement is 1.5 quarts divided by 100 gallons, which equals 0.015 quarts per gallon.

Next, to find the amount needed for 45 gallons, multiply the per gallon amount (0.015 quarts) by 45 gallons:

0.015 quarts/gallon * 45 gallons = 0.675 quarts.

This means that for 45 gallons, you will need 0.675 quarts of surfactant. The correct choice reflects this calculation. It illustrates the important concept of scaling quantities based on the proportions specified in the instructions.