RAS question
In a row of children, Anil is 14th from the left and Sunil is 10th from the right. If they interchange their positions, Anil becomes 25th from the left. How many children are in the row?
Correct answer: (D) 34.
There are 34 children in the row because Sunil's 10th position from the right becomes Anil's 25th position from the left after the interchange.
Explanation
After the interchange, Anil stands exactly where Sunil had been standing, so Anil's new rank from the left is also Sunil's original rank from the left. The cited ranking-order rule is that a position from the opposite side is found by using the total number in the row, the known position from one side, and 1. Here, Sunil is 10th from the right and, after the swap, that same place is 25th from the left. Therefore, total children = left rank + right rank - 1 = 25 + 10 - 1 = 34. Anil's original 14th position from the left only sets up the interchange; the total is fixed by Sunil's right-side rank and Anil's new left-side rank.
Why the other options are wrong
- (A) 32 would imply that the position which is 10th from the right is 23rd from the left, not 25th.
- (B) 33 would place Sunil's original position 24th from the left, so Anil could not become 25th from the left after the swap.
- (C) 35 would make the 10th position from the right equal to 26th from the left, overshooting Anil's stated new position by one.
Concept
This tests ranking and order in a row, especially converting a position from the right into a position from the left after an interchange. It recurs in RAS reasoning because the examiner can test a simple formula while checking whether the candidate tracks whose position changes.