From the given responses, find the missing letter in the series. AA, BD, CI, DP, ?

NHM MP Staff Nurse-2022

Reasoning

Hard

Appeared in: NHM MP Staff Nurse-2022

Explanation

The series consists of two independent patterns, one for the first letter of each pair and one for the second.
The first letter of each pair follows a simple alphabetical sequence: A, B, C, D. The next letter is E.
The second letter's position in the alphabet is the square of the first letter's position. For A (1), the second letter is A (1²=1). For B (2), the second letter is D (2²=4). For C (3), the second letter is I (3²=9). For D (4), the second letter is P (4²=16).
Following this rule, for the next term starting with E (5), the second letter's position will be 5², which is 25.
The 25th letter of the English alphabet is Y.
Combining the two patterns gives the next term as EY.

Option A: The first letter 'F' is incorrect as it skips 'E' in the alphabetical sequence. The second letter 'R' (18th position) does not fit the pattern of perfect squares.
Option B: While the second letter 'Y' (25th position) correctly follows the perfect square pattern (5²), the first letter 'F' is incorrect because it breaks the simple A, B, C, D, E sequence.
Option C: The first letter 'E' is correct, but the second letter 'R' (18th position) is incorrect. The pattern requires the second letter to be the square of the first letter's position (5² = 25), which corresponds to 'Y', not 'R'.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain This question tests the ability to identify and apply dual patterns in a letter series, a common type of logical reasoning problem as background academic context rather than a clinical decision trigger.
While not a clinical question, logical reasoning is a critical skill for nurses. It is used in prioritizing patient care, interpreting diagnostic data, and troubleshooting equipment.
Pattern recognition helps in identifying trends in a patient's vital signs or symptoms, which can indicate improvement or deterioration.
What if? - If the second letter pattern was 'position x 3' instead of 'position squared', the series would be AC (1x3), FF (2x3), II (3x3), LL (4x3), and the next term would be EO (5x3=15).

How to Approach the Question

First, analyze the question to understand it's a letter series problem requiring you to find the next term.
Break the problem down. Notice that each term is a pair of letters. Treat the first letters of each pair as one series and the second letters as another.
Analyze the first letter series: A, B, C, D. This is a straightforward alphabetical progression. The next letter must be E.
Analyze the second letter series: A, D, I, P. This pattern is not immediately obvious. Convert the letters to their numerical positions in the alphabet: 1, 4, 9, 16.
Recognize that the numerical series (1, 4, 9, 16) consists of perfect squares (1², 2², 3², 4²).
Determine the next number in the sequence, which is 5² = 25. Convert this number back to a letter. The 25th letter is Y.

Concept Tested & Keywords

Concept Tested: This question tests the ability to identify and apply dual patterns in a letter series, a common type of logical reasoning problem.
Stem keywords: missing letter, series, AA, BD, CI, DP
Lead-in keywords: find

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