Structural Pest Control Applicator Practice Exam

How many pounds of 25 percent WP must you add to 100 gallons of water to achieve a 1 percent active ingredient mixture?

1. 25.5 lbs

2. 30.5 lbs

3. 33.2 lbs

4. 40.0 lbs

The correct answer is: 33.2 lbs

To determine how many pounds of a 25 percent wettable powder (WP) you need to combine with 100 gallons of water to achieve a 1 percent active ingredient mixture, we need to set up the equation based on the concentration and volume of the mixture. First, we need to calculate the total amount of active ingredient needed in the final mixture. Since you want a 1 percent concentration in 100 gallons of water, you will need: 1 percent of 100 gallons = 1/100 × 100 gallons = 1 gallon of active ingredient. Next, since 1 gallon is equivalent to approximately 8.34 pounds (the weight of a gallon of water), this indicates you need about: 1 gallon × 8.34 pounds/gallon = 8.34 pounds of active ingredient. Now, since the WP is 25 percent active ingredient, we can determine how much of this product is required to yield 8.34 pounds of the active ingredient. The formula to derive the amount of wettable powder needed is: Amount of WP = Amount of active ingredient needed / Percentage concentration. Substituting the known values: Amount of WP = 8.34 pounds / 0.25 = 33.36 pounds