# Chain Rule

#### Video Lesson on Chain Rule

Chain rule is commonly applied in Ratios and proportions questions when more than two ratios are inter-related.

## Points to Remember

### 1) Direct Proportion:

Any two quantities are said to be directly proportional, if on the increase of one quantity, the other quantity increases and vice-versa.

• Example: Cost is directly proportional to number of objects
Cost ? Number of objects
Number of objects increases (↑) Cost (↑)
• Example: Work done is directly proportional to number of working men
Work done ? Number of working men
Number of men increase (↑) Work done (↑)  ### 2) Indirect Proportion:

Any two quantities are said to be indirectly proportional, if on the increase of one quantity, the other quantity decreases and vice-versa.

• Example: If speed of car is increases, then the time required to cover the distance decreases.
Speed of car (↑) Time required decreases (↓)
• Example: Time taken to finish work increases, if number of men decrease.
Time (↑) Number of men (↓)

### Tips and Tricks

In this chapter generally different types of numerical related to time and work, time and speed, cost and number of articles, men and work, etc. are asked.

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