Which formula is used to determine pounds of chemical per cubic feet per second (CFS)?

The formula that accurately determines pounds of chemical per cubic feet per second (CFS) is constructed to account for the total weight of a chemical in relation to the flow rate and duration of application. The correct choice focuses on converting measurements to achieve the desired calculation of active ingredient concentration.

The given formula involves first calculating the total amount of chemical based on parts per million weight (PPMW), then adjusting for the total volume being treated by factoring in the time (in minutes) of herbicide application. By multiplying by 3,744—which relates to the conversion from gallons to cubic feet and the need for time in minutes—this formula effectively uses these units to ultimately deliver the concentration in pounds per CFS.

In contrast, the other options do not accurately formulate the relationship needed to calculate the pounds of chemical effectively per CFS. For instance, the other formulations do not tie the components together in a way that reflects both the flow rate and the appropriate duration needed for proper treatment calculations. Thus, while they may present relevant factors, they lack the comprehensive structure found in the correct formula.