Proportion Calculator
Solve a proportion (a/b = c/d) for the missing value using cross-multiplication.
D (missing value)
16.0000
D (missing value) vs A (numerator 1)
Formula
## How to Solve a Proportion ### Formula **If A/B = C/D, then D = (B * C) / A** A proportion is an equation stating that two ratios are equal. Cross-multiplication gives A*D = B*C. Solve for any missing value by rearranging. This is fundamental to scaling, unit conversion, and similar triangles.
Exemplo Resolvido
If 3/4 = 12/x, find x.
- 01Cross-multiply: 3 * x = 4 * 12
- 023x = 48
- 03x = 48 / 3 = 16
- 04Check: 3/4 = 0.75, 12/16 = 0.75. Confirmed.
Perguntas Frequentes
What is a proportion used for?
Proportions are used for scaling recipes, map distances, currency conversion, unit conversion, similar figures in geometry, and any problem where two ratios must be equal.
Is a proportion the same as a ratio?
A ratio compares two values (A:B). A proportion is an equation stating two ratios are equal (A:B = C:D). All proportions involve ratios, but not all ratios are part of a proportion.
Can proportions work with negative numbers?
Mathematically yes, cross-multiplication works with any nonzero values. However, proportions are most commonly used with positive quantities in applied contexts.
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