Order and Ranking
Order and Ranking helps us understand positions in a group. It tells us exactly where someone stands in a line or a list. This group can be a horizontal row or a vertical list. Imagine standing in a queue for movie tickets. You have a rank from the front. You also have a rank from the back. These two ranks help us calculate the total number of people.
In competitive exams, we focus on three main pieces of data. First is the total number of people in the group.
Concepts (3)
To find the total number of people in a row, you need the rank of one person from both ends. You add the rank from the left and the rank from the right. Then, subtract one from the sum. This is because that person is counted twice.
To find the total number of people in a row, you need the rank of one person from both ends. You add the rank from the left and the rank from the right. Then, subtract one from the sum. This is because that person is counted twice. Example: If Ravi is 10th from the left and 12th from the right, Total = (10+12) - 1 = 21.
If you know the total number of people and a person's rank from one side, you can find their rank from the other side. Subtract the known rank from the total. Finally, add one to the result.
If you know the total number of people and a person's rank from one side, you can find their rank from the other side. Subtract the known rank from the total. Finally, add one to the result. Example: In a row of 50 students, if Amit is 20th from the top, his rank from the bottom is (50-20) + 1 = 31st.
In these problems, two people swap their places. After the swap, the new rank of one person is usually given. You use this new rank and the old rank of the second person to find the total.
In these problems, two people swap their places. After the swap, the new rank of one person is usually given. You use this new rank and the old rank of the second person to find the total. Example: If A moves to B's old spot, A's new position from the left and B's old position from the right can find the total.
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Start Lesson: Finding the Total