FORMULA SHELF
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The arithmetic behind the work: what to measure, what to type in, and what the answer comes out as. Every formula says what the symbols mean and gives a worked example, so you can check it against a job you have already done.
SHELVES
Data
4 formulas
Average feed analysis across different batches, average yield across fields of different sizes, average price across different volumes sold.
Field A: 10 ha at 6 t/ha, field B: 4 ha at 4 t/ha gives (60 + 16) / 14 = 5.43 t/ha.
How spread out a set of readings is. A 500 litre herd with a standard deviation of 20 is steady; one with 120 is not. It is how you tell a genuinely consistent flock from a lucky average.
Readings 98, 100, 102, 100 give a mean of 100 and a standard deviation of about 1.6.
Averages lie when one reading is odd. The median tells you the typical day; the range tells you how variable the month was. Use both for milk records, daily temperatures and yields.
10, 12, 12, 13, 20 litres: median 12, range 10.
For a sprayer that does not deliver its rated volume, a scale that reads light, or a soil test that is out by a tenth of a point. Know the error and you can correct for it.
A 20 L/min sprayer that delivers 18: error = -10%.
Convenience only. Double-check the result against the worked example or a second method before you use it.
SOURCES & PROVENANCE
1 listed
This page is an AI-organised index. The label means the grouping and cross-links were compiled with AI; the information itself comes from the public-domain books, reports and manuals listed below. Open any source to read the local copy or follow the link to the original publication.