Machines × Days
- Input
- A=4, B=6, C=8
- Expected output
- X = 3
8 machines finish in 3 days.
inverse rule of three
Inverse Rule of Three
In an inverse proportion, the product of quantities is constant: A × B = C × X, so X = A × B / C.
What is an inverse proportion
- When one quantity doubles and the other is halved, we have an inverse proportion. Example: speed and time for a fixed distance.
- 4 machines finish a job in 6 days. With 8 machines: X = 4 × 6 / 8 = 3 days.
Examples
Safe use
- Input
- context + tool result
- Expected output
- interpreted with limits and next steps
Use the result as technical or educational support, keeping the tool limits explicit in the workflow.
Full tool FAQ
In a direct proportion, two quantities grow or shrink together. If A is to B as C is to X, then X = B × C / A. Example: 3 workers produce 6 items per day; 5 workers would produce 10.
Frequently asked questions
What is a constant product?
In inverse proportion, A × B = C × X = k (constant). k is the invariant of the relationship.
Does this page replace official or professional review?
No. It helps explain the scenario and use the tool more safely, but real decisions should consider official sources, full context and qualified guidance when needed.