Refer to the following number series and answer the question that follows. Counting to be done from left to right only. (All numbers are single-digit numbers only.)

(Left) 5 2 4 7 8 5 7 3 1 5 4 9 2 1 3 4 8 (Right)

How many such even digits are there, each of which is immediately preceded by an odd digit and also immediately followed by an odd digit?

1. A

   4

2. B

   2

3. C

   1

4. D

   3

Appeared in: Bihar NHM CHO-2025

Explanation

• The question requires identifying a specific three-digit pattern: an even number that has an odd number on both its immediate left and immediate right.
• The pattern to search for is: Odd-Even-Odd.
• Scanning the series reveals three such occurrences: '7 8 5', '5 4 9', and '9 2 1'.
• The even digits that fit this condition are 8, 4, and 2.
• Counting these occurrences gives a total of 3.

Why Other Options Were Wrong

• Option A: A count of 4 is incorrect. This might result from misidentifying an even or odd number or incorrectly checking the preceding/following digits.
• Option B: A count of 2 is incorrect. This indicates that one of the three valid patterns was missed during the scan of the number series.
• Option C: A count of 1 is incorrect. This suggests that two of the three valid patterns were overlooked, possibly by stopping the search after finding the first match ('7 8 5').

Related Visual

• Visual 1: Infographic: A visual representation of the number series with the three 'Odd-Even-Odd' patterns ('7 8 5', '5 4 9', '9 2 1') highlighted in different colors to make them stand out.

Clinical Relevance

• Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Logical Reasoning - Number Series Analysis as background academic context rather than a clinical decision trigger.
• This question is not related to a clinical nursing topic. It assesses logical reasoning and attention to detail.
• These skills are foundational for nurses who must accurately interpret data, follow multi-step protocols, and identify patterns in patient symptoms or vital signs.
• What if the question asked for even digits followed by an odd digit? The answer would change. For example, '2' in '2 4 7' would not count, but '4' would. The count would be different, highlighting the need to read instructions precisely.

How to Approach the Question

• First, understand the exact condition: you need to find an EVEN digit.
• Second, understand the constraints on this even digit: it must be 'immediately preceded by an odd digit' AND 'immediately followed by an odd digit'.
• This translates to a three-number sequence: ODD - EVEN - ODD.
• Systematically scan the series from left to right. When you encounter an even number, pause and check the digit before it and the digit after it.
• Keep a running count of every time the ODD-EVEN-ODD condition is met.
• After checking all even numbers in the series, the final count is your answer.

Concept Tested & Keywords

• Concept Tested: Logical Reasoning - Number Series Analysis
• Stem keywords: number series, even digits, odd digit, immediately preceded, immediately followed
• Lead-in keywords: How many

Question ID

QE2EXx31hhEIdVIOcuRaHy

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