Price by weight
- Input
- A=3, B=9, C=5
- Expected output
- X = 15
5 kg at $3/kg = $15.
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direct rule of three
In a direct proportion, when one quantity increases, the other increases at the same rate. X = B × C / A.
5 kg at $3/kg = $15.
3.5 km = 3500 m.
In a direct proportion, two quantities grow or shrink together: doubling one doubles the other. You set up A/B = C/X and isolate the unknown with X = B × C / A. For example, if 3 workers produce 6 items per day, 5 workers produce X = 6 × 5 / 3 = 10 items, because more labor yields more output in the same proportion.
If quantities grow together, it is direct. If one grows and the other shrinks, it is inverse.
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.
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