UPSC Prelims 2014·CSAT·Logical Reasoning·Arrangement and Puzzles

In a row 'A' is in the 11th position from the left and 'B' is in the 10th position from the right. If 'A' and 'B' interchange, then 'A' becomes 18th from the left. How many persons are there in the row other than 'A' and 'B'?

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Last updated 23 May 2026, 3:31 pm IST
  1. A27
  2. B26
  3. C25Correct
  4. D24

Explanation

Here's a brief explanation: 1. After A and B interchange positions, A moves to B's original spot. 2. A is now 18th from the left. This means B's original position was 18th from the left. 3. We also know B was 10th from the right. 4. To find the total number of persons in the row, use the formula: Total = (Position from left) + (Position from right) - 1. 5. Total persons = 18 (B's position from left) + 10 (B's position from right) - 1 = 28 - 1 = 27. 6. The question asks for the number of persons *other than* A and B. 7. Persons other than A and B = Total persons - 2 (for A and B) = 27 - 2 = 25. Therefore, there are 25 persons in the row other than A and B. The final answer is C) 25.
Logical Reasoning: In a row 'A' is in the 11th position from the left and 'B' is in the 10th position from the right. If 'A' and 'B' interc

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