Chain Rule

Quantitative Aptitude - Chain Rule

Use chain rule to relate variables via intermediate ratios.

1. Core Concept

If A:B = x and B:C = y, then A:C = x×y.

2. Applications

• Unit conversion (e.g., cost per kg → cost per g).
• Linked averages (e.g., cost per dozen to per piece).

3. Quick Tips

• Write step-by-step ratios and cancel common terms.
• Use sequential multiplication of conversion factors.

4. Common Errors

• Reversing ratios incorrectly.

5. Revision Checklist

• Master chaining of 3+ ratios.

Summary: Multiply sequential ratios to find indirect relations; treat units as variables, cancel consistently, and simplify final ratio.