Rule of Three Calculator
Solve rule-of-three problems easily and quickly. Direct and inverse proportion with calculation steps. Step-by-step explanation, free and no registration.
The more, the more: If A belongs to B, how much belongs to X?
Known assignment
If A ⇒ B, then X ⇒ ?
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Note: These calculations are for informational purposes only and do not replace professional tax or financial advice. All information without guarantee.
Frequently Asked Questions
What is the rule of three?
The rule of three is a method for proportional calculations. Given three known values, you can find the fourth. Set up the proportion, cross-multiply, and divide to find the unknown value.
What is the difference between direct and inverse proportionality?
In direct proportionality, both values increase together (more workers = more output). In inverse proportionality, as one increases the other decreases (more workers = less time per task).
What is the Rule of Three Calculator?
The rule-of-three calculator solves proportional and inversely proportional problems in three steps and shows the full solution path.
How does the Rule of Three Calculator work?
Choose proportional or inversely proportional. Enter three known values. The calculator solves in three steps: starting situation, reduce to one unit, scale to the target value. Each step is explained.
Key Data and Facts
Proportional: x = (b * c) / a. Inversely proportional: x = (a * b) / c. Applications: prices, recipe quantities, working time, currencies.
Step-by-Step Guide
So loesen Sie Dreisatz-Aufgaben step by step: 1. Zuordnungsart bestimmen: Proportional (je mehr, desto mehr) oder antiproportional (je mehr, desto weniger). 2. Ausgangssituation aufschreiben: Zwei zusammengehoerige Werte, z. B. 5 Aepfel costs 3 EUR. 3. Auf die Einheit rechnen: Bei proportional: 1 Apfel = 3 / 5 = 0,60 EUR. Bei antiproportional: Produkt bilden: 5 x 3 = 15. 4. Auf den Zielwert hochrechnen: Proportional: 8 Aepfel = 0,60 x 8 = 4,80 EUR. Antiproportional: 8 Arbeiter brauchen 15 / 8 = 1,875 hours. 5. Typische Anwendungen: Rezepte umrechnen (proportional), Preise compare, Waehrungen umrechnen, Arbeitszeit-Aufgaben (antiproportional). 6. Kurzformel proportional: x = (b x c) / a. Kurzformel antiproportional: x = (a x b) / c. Der Rechner zeigt jeden Schritt einzeln an.
Calculation Example
Proportional: 5 Aepfel costs 3 EUR. 8 Aepfel? 1 Apfel = 3/5 = 0,60 EUR. 8 Aepfel = 8 x 0,60 = 4,80 EUR. Antiproportional: 6 Arbeiter brauchen 10 days. 4 Arbeiter? 6 x 10 / 4 = 15 days.
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