What will you learn from this article?
- Concept of Ranking
- Different Formulas and tricks for solving questions
- Types of questions seen in the examinations
Ranking questions can be very tricky and time-consuming if the student is unaware of the tips and formulae of the ranking concept. It is one of the standard topics seen in all of the competitive examinations. It is a short topic but with high mark weightage.
What is Ranking?
In this topic, we would be given a scenario wherein a group of people or objects are placed in a straight line, and we have to find the rank of a particular person or object from either side of the line. There are two logical ways to find the ranks:
- Manually (which is very time consuming and error-prone)
- Applying some tricks and formulae (which is quicker and less error-prone)
Example Question: Rahul is ranked 17th from the right end of the row and 16th from the left end of the row. How many students are standing in the row?
Solution: Since Rahul is ranked 17th from the right end of the row, that means 16 students are standing on the right side of Rahul.
Also, Rahul is ranked 16th from the left end of the row, that means 15 students are standing on the left side of him.
So total no. of students standing in the row would be
= 15 + 16 + 1
Note: The 1 added in the final answer represents Rahul himself, who earlier was excluded in the calculation process.
Let ‘T’ be the total number of people in the row.
Let ‘L’ be the person’s position from the left side.
Let ‘R’ be the person’s position from the right side.
- A person’s position from the right end, whose position from the left end is given = T – L + 1
- A person’s position from the left end, whose position from right end is given = T – R + 1
- Total number of people standing in the row = L + R – 1
Common mistake: Students often get confused between the number of people in between and the rank of an individual. For example, a student having 10th rank from the left will not have 10 students to his left, he will have 9 students on his left.
Example Question: Rohan is standing at the 6th position from the left end, whereas Keshav, his friend, is standing 20th from the right end. If 10 boys are standing in between them, then how many boys are there in the row?
Solution: We have the respective position of both the friends from both the sides and the number boys in between them, to find the total number of boys in the whole row, we first have to find the ranking of any one of the friends, from both left and right side.
We have to be careful while computing the position of let’s say Keshav because no. of boys between them is 10; hence, his position from the left end would be 17th and not 16th.
So total no. of boys standing in the line is
= Keshav’s position from left + Keshav’s position from right – 1
= 17 + 20 – 1
To read the previous topic on Order, please click here.