## Chain Rule

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Chain Rule – General Questions Practice different types of aptitude test for free, including numerical and verbal tests. All questions come with worked solutions to help you improve.

Chain Rule can be applied in questions where two or more than two elements are given. Each element has two figures except one element that has one part missing. Chain rule is used to find out this missing part of an element by subsequent comparison. The other given part of the same element is taken as base and is compared separately with all the other elements e.g. if you have a question having following elements: ‘men’, ‘days’ and ‘hours’. Let us say ‘hours’ are missing then you will compare ‘hours’ with all the other elements independently. Here independently means, comparing ‘hours’ with ‘men’ ignoring the element- ‘days’. Similarly while comparing ‘hours’ and ‘days’ you will ignore the element- ‘men’.

## chain rule formula

*Direct Proportion:*Two quantities are said to be directly proportional, if on the increase (or decrease) of the one, the other increases (or decreases) to the same extent.Eg. Cost is directly proportional to the number of articles.

(More Articles, More Cost)*Indirect Proportion:*Two quantities are said to be indirectly proportional, if on the increase of the one, the orther decreases to the same extent and vice-versa.Eg. The time taken by a car is covering a certain distance is inversely proportional to the speed of the car. (More speed, Less is the time taken to cover a distance.)*Note:*In solving problems by chain rule, we compare every item with the term to be found out.

**Chain rule**** Principle**

After the comparison, the following two principles are followed:

- If the missing part is greater than the given part, then the numerator (n) is kept greater than the denominator (d) i.e. n/d>1, where n & d are the given parts of other element.
- If the missing part is smaller than the given part, then the numerator (n) is kept smaller than the denominator (d) i.e. n/d<1, where n & d are the given parts of other element.