How the problems work
Pick topics and a number of problems. Each set gets a code, and a class link carries the code and every setting, so each student who opens it gets the same numbers. Products are made up and rates are practice values in a realistic range.
Answers are worked at full precision and rounded once, at the end, unless you choose to round each step. Wrong answers that come from a known slip get a hint: fluid ounces per minute used as GPM, a band treated as broadcast, the percent a.i. multiplied instead of divided, the diameter used as the radius, or the right amount in the wrong unit.
The Core Manual's calibration example, worked the same way
A boom sprayer used 10 gallons of water on a 0.25-acre test area, and the label calls for 4 fl oz of product per gallon of spray. To treat 10 acres:
- Spray: 10 gal ÷ 0.25 acre = 40 gallons per acre, × 10 acres = 400 gallons.
- Product: 400 gal × 4 fl oz = 1,600 fl oz.
- In gallons: 1,600 ÷ 128 = 12.5 gallons of product in 400 gallons of mix.
Try six tank and mixing problems
Formulas and where they come from
| What | Formula | Source |
|---|---|---|
| Area | L × W; base × height ÷ 2; 3.14 × r × r; ÷ 43,560 for acres | Core Manual (2014) p. 164; Oregon PSEP (2025) |
| Tank | acres per tank = tank ÷ GPA; product = acres per tank × rate | Core Manual App. C p. 190-191; K-State MF3100 |
| Active ingredient | lb a.i. ÷ (% a.i. ÷ 100); lb a.i. ÷ lb a.i. per gal | Core Manual App. C p. 191; AgriLife (2026) |
| Band | treated acres = field acres × band ÷ row spacing | Ohio State key (2019); Oregon PSEP (2025) |
| Boom GPA | GPM × 5,940 ÷ (mph × W in); or × 495 with W in feet; or fl oz/min × 46.4 | Oregon PSEP; UNL (2026); AgriLife (2026) |
| Speed | mph = feet × 60 ÷ (seconds × 88) | Oregon PSEP; AgriLife (2026) |
| 1/128 acre | 340 sq ft; course = 4,084 (4,083.75 exact) ÷ spacing in inches; fl oz caught = GPA | CTAHR PRRE-7 (2013); Kentucky ENTFACT-804 (2025) |
| Granular | lb ÷ (swath × run) × 1,000 = lb per 1,000 sq ft | Oregon PSEP (2025) |
Sources checked October 24, 2026. The National Core Manual's 3rd edition (PERC) is sold in print and as an eBook, and some states now study from it; this page follows the free 2nd edition and the state materials above.
Questions
How do you calculate gallons per acre for a boom sprayer?
GPA = GPM × 5,940 ÷ (mph × nozzle spacing in inches). Change fluid ounces per minute to GPM first by dividing by 128. Oregon State's example: 35 fl oz per minute is 0.273 GPM, and at 4 mph with 20-inch spacing that is 20.3 GPA.
What is the 1/128-acre calibration method?
1/128 acre is about 340 sq ft and a gallon is 128 fl oz, so the fluid ounces you catch in the time it takes to spray 1/128 acre equal the gallons per acre. For a boom, the course is 4,084 (4,083.75 exact) ÷ nozzle spacing in inches: 204 ft for 20-inch spacing.
How much product goes in the tank?
Divide the tank size by the gallons per acre to get the acres one tank covers, then multiply by the rate per acre. The Core Manual's example: a 400-gallon tank at 15 GPA covers 26.7 acres, so at 3 lb per acre it takes 80 lb.
How do you convert pounds of active ingredient to product?
For a dry product, divide the pounds of a.i. by the percent a.i. as a decimal: 2 lb a.i. of an 80% WP is 2 ÷ 0.8 = 2.5 lb. For a liquid, divide by the pounds of a.i. per gallon: 2 lb a.i. of a 4 lb per gallon EC is 0.5 gallon.
How is a band rate different from a broadcast rate?
In a band only part of the field is sprayed. Treated acres = field acres × band width ÷ row spacing, so 24-inch bands on 36-inch rows in a 2-acre field treat 1.33 acres. Product is the broadcast rate times the treated acres.
Will I get a formula sheet on the exam?
That depends on your state and category. Oregon's study course says its exam provides the formulas and conversions, and AgriLife's Texas calibration practice says a formula list is given. Ask your state agency, and practice with the formula box off if you are not sure.
Are these real product rates?
No. The products are made up (Herbicide A, Insecticide C) and the rates are practice values in a realistic range. For a real application, always follow the product label: the label is the law.
How do I give my whole class the same problems?
Pick the topics, number of problems and conventions, then tap Share with class and send the link. It always opens the same set, even if the defaults here change later. Print the answer key for yourself.
This page teaches exam arithmetic. It is not advice for a real application.
Sources: National Pesticide Applicator Certification Core Manual, 2nd ed., 2014 (PDF); Oregon State PSEP, Pesticide Math, February 2025 (PDF); Ohio State pesticide math answer key (PDF); UNL pesticide math worksheets; Texas A&M AgriLife, Calibration Problems for Pesticide Applicators (PDF); Texas A&M AgriLife, Right of Way Pest Control practice problems (PDF); K-State MF3100, Calculating Pesticide Measurements, 2013; CTAHR PRRE-7, Sprayer Calibration Using the 1/128th Method, 2013 (PDF); Kentucky ENTFACT-804, 2025 (PDF).