Rule No. 5

When in a single row, the positions of two persons are given and their positions are interchanged and after interchanging the position of first person is given from the same side as before interchanging.

a) To find the total number of persons of that row:

Formula:

Total Number of persons = Sum of the particular positions of a place (different person) from both sides – 1

Example:

In a row of persons, Ashish is 11th from the left and Salman is 20th from the right. If they interchange their positions, then Ashish becomes 17th from the left. Find out the total number of persons of that row.

Solution:

Total Number of persons = Sum of the particular positions of a place (different person) from both sides – 1

 Positions of Salman before change + position of Ashish after change – 1  

 20 + 17 – 1 = 36

Hence, there are 36 persons.  

b) To find the new position of the second person from the same side as before interchanging:

Formula:

The position of the second person from the same side as before interchanging = The position of the second person from the same side before interchanging + (position of the first person after interchanging – position of the first person before interchanging from the same side

Example:

In a row of persons, Ashish is 11th from the left and Salman is 20th from the right. If they interchange their positions, then Ashish becomes 17th from the left. Then, what will be the new position of Salman from the right end?

Total no of persons in a row = Position from the right end + Position from the left end – 1  

= 20 + 17 – 1 = 35  

Salman’s position from right end = Total persons – Ashish’s position from the left end + 1  

= 36 – 10 + 1 = 27

Hence, in the new arrangement, the position of Salman is 27th from the right end.

c)  To find the number of persons between that two persons:  

Formula:

Number of persons between two persons = Difference in the positions of a person (same person) whose position from same side before and after interchanging is given – 1

Example:

In a row, Avni is 14th from the left end and Tanmay is 13th from the right end of the row. If they interchanged their positions Avni becomes 19th from the left end. Find the number of persons between them.

Solution:

Number of persons between Avni & Tanmay = (Position of Avni from left after interchanging– Position of Avni from left before interchanging) – 1  

⇒ Number of persons between Avni & Tanmay is = (19 – 14) – 1 = 5 – 1 = 4

There are many different types of questions that are asked from the order and ranking topic. Those questions are generally related to rank from the left, right, top, and bottom, the total number of persons, products or elements, etc. Thus, many different types of questions can be formed based on the position or the rank of the persons, things, or products. In this topic, we will discuss how the concepts of Order and Ranking works. Let us understand, it with the help of the important rules: