UPSC Prelims 2021·CSAT·Logical Reasoning·Coding Decoding

In the English alphabet, the first 4 letters are written in opposite order; and the next 4 letters are written in opposite order and so on; and at the end Y and Z are interchanged. Which will be the fourth letter to the right of the 13th letter?

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Last updated 8 Jul 2026, 4:39 pm IST
  1. AN
  2. BTCorrect
  3. CH
  4. DI

Explanation

Here's a step-by-step breakdown:

  1. Reorder the alphabet based on the given rules:

    • Original: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
    • First 4 reversed: D C B A
    • Next 4 reversed: H G F E
    • Next 4 reversed: L K J I
    • Next 4 reversed: P O N M
    • Next 4 reversed: T S R Q
    • Next 4 reversed: X W V U
    • Last 2 interchanged: Z Y

    The new alphabet sequence is: D C B A H G F E L K J I P O N M T S R Q X W V U Z Y

  2. Identify the 13th letter in this new sequence: 1st: D 2nd: C 3rd: B 4th: A 5th: H 6th: G 7th: F 8th: E 9th: L 10th: K 11th: J 12th: I 13th: P

    The 13th letter is P.

  3. Find the fourth letter to the right of the 13th letter (P): Starting from P, move four positions to the right in the new sequence: 1st to the right of P: O 2nd to the right of P: N 3rd to the right of P: M 4th to the right of P: T

    The fourth letter to the right of P is T.

  4. Compare with options: The calculated letter is T, which matches option B.

The final answer is B) T.

Logical Reasoning: In the English alphabet, the first 4 letters are written in opposite order; and the next 4 letters are written in opposi

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