Class 8 Math: Direct and Inverse Proportions Quick Revision Chapter Summary

Need to review the entire chapter before a test? This quick revision guide summarizes all the core concepts, topics, and equations taught in Class 8 Direct and Inverse Proportions to help you refresh your memory instantly.

Core Topics At a Glance

### 📌 Direct proportion concept Two quantities are in direct proportion if an increase in one leads to a proportional increase in the other, keeping their ratio constant.

### 📌 Inverse proportion equations Two quantities are in inverse proportion if an increase in one leads to a proportional decrease in the other, keeping their product constant.

### 📌 Time and Work scenarios Problems involving multiple workers or pipes, modeled using inverse proportion (more workers means less time taken).

### 📌 Speed and travel times proportion Speed and travel times are inversely proportional when the total distance remains constant.

Key Formulas Mind Map

• Direct Proportion: `\frac{x_1}{y_1} = \frac{x_2}{y_2}` - Ratio remains constant....
• Inverse Proportion: `x_1 y_1 = x_2 y_2` - Product remains constant....

Revision Checklist

1. Review the subtopic guides and outline notes.
2. Practice writing the key formulas from memory.
3. Solve at least 3 worked examples and check your steps.
4. Take a timed practice quiz to verify your speed.