RAS question
In a queue, Amit is 10th from the front and 15th from the back. How many people are in the queue?
Correct answer: (A) 24.
Amit's queue has 24 people, since a person who is 10th from the front and 15th from the back is counted once from each side: 10 + 15 - 1 = 24.
Explanation
This is a direct number-ranking problem based on position from opposite ends of a line. SATHEE's Number Ranking material gives the relation as position from top or front plus position from bottom or back equals total number plus 1. So, when Amit is 10th from the front and 15th from the back, the two counts include Amit twice. To get the actual queue length, add the two positions and subtract 1 for Amit's double counting: 10 + 15 - 1 = 24. The subtraction is the key step; without it, the same person would be treated as two different people.
Why the other options are wrong
- (B) 25 comes from adding 10 and 15 directly, which double-counts Amit instead of subtracting 1.
- (C) 23 subtracts one person too many; the formula needs only one subtraction because only Amit is counted from both ends.
- (D) 26 would result from adding an extra person, but opposite-end ranking requires subtracting 1, not adding 1.
Concept
This tests number ranking through positions from opposite ends of a line. It recurs in RAS reasoning because queue, rank and order questions reward fast handling of inclusive counting.