To batch mix 3% foam into a 500-gallon (1894 L) booster tank, you would need to add _____ of foam concentrate to the tank.

The correct calculation to determine how much foam concentrate is needed for a 3% foam mix involves using the volume of the booster tank and the desired percentage concentration. In this case, you have a 500-gallon tank and want to create a 3% foam solution.

To calculate the required volume of foam concentrate, you take 3% of the total volume of the liquid in the tank.

This is done by multiplying the total volume (500 gallons) by the percentage expressed as a decimal (3% = 0.03):

500 gallons x 0.03 = 15 gallons.

This means that to create a 3% foam solution in a 500-gallon tank, you need to add 15 gallons of foam concentrate.

Therefore, the answer that correctly indicates the amount of foam concentrate needed for the specified dilution in the booster tank is 15 gallons.