Proportion Calculator
Proportion Calculator
Find X in a : b = c : x
Introduction
The Proportion Calculator shows what an unknown fourth value will be when three related values are known — a simple tool for solving ratios and proportional relationship problems in real life.
How to Use
- Enter three known values (A, B, and C, where A/B = C/D)
- The unknown value (D) is calculated automatically
- Click "Calculate" — the result displays instantly
Formula Explanation
If A/B = C/D, then D = (B × C) / A (cross-multiplication method)
Worked Example
If 2 kg of flour costs ₹80, how much would 5 kg cost? Using proportion: 2/80 = 5/D, giving D = (80 × 5)/2 = ₹200.
Practical Context
Proportion is widely used in India for scaling cooking recipes (e.g., scaling a recipe for 2 people to serve 6), calculating business ingredient ratios, and in school mathematics as part of the ratio-proportion chapter. Competitive exams also frequently feature ratio-proportion based quantitative aptitude questions.
Frequently Asked Questions
Q1: What's the difference between ratio and proportion?
A ratio compares two quantities (e.g., 2:3), while a proportion shows the equality of two ratios (e.g., 2:3 = 4:6) — a proportion always involves four values.
Q2: What's the difference between direct and inverse proportion?
In direct proportion, both quantities change in the same direction (one increases, the other increases too), while in inverse proportion, they change in opposite directions (one increases, the other decreases).
Q3: How does the cross-multiplication method work?
If A/B = C/D, then A×D = B×C — this equality allows any unknown value to be easily solved.
Q4: How is proportion used in map scale calculations?
Map scales use proportion to relate map distance to real-world distance — knowing the scale ratio and one distance lets you calculate the corresponding real or map distance.
Q5: Can proportion be used with more than two ratios?
Yes, this is called "continued proportion," where multiple ratios are equal to each other in sequence, commonly used in more advanced mixture and ratio problems.