If your rate of application is 5 gallons per acre and your tank holds 100 gallons, how many pounds of formulation must you add to apply 2 pounds per acre?

To calculate the amount of formulation needed, we begin by determining how many acres can be covered with the tank's capacity. A tank that holds 100 gallons and a rate of application of 5 gallons per acre means that the tank can cover:

[ \text{Coverage} = \frac{100 \text{ gallons}}{5 \text{ gallons per acre}} = 20 \text{ acres}

]

Next, since the desired application rate is 2 pounds per acre, we can calculate the total amount of formulation needed for those 20 acres:

[ \text{Total formulation needed} = 20 \text{ acres} \times 2 \text{ pounds per acre} = 40 \text{ pounds} ]

Therefore, to achieve the application of 2 pounds of formulation per acre over the area that can be covered by the 100-gallon tank, you must add 40 pounds of formulation. This shows that the calculation for the correct answer revolves around understanding the relationship between the tank capacity, the application rate, and the desired formulation rate, leading to the conclusion that 40 pounds is necessary for the intended coverage.