Which is a wrong term in the number series? 24,27,31,33,36

Appeared in: HPSSC Staff Nurse - 2021

Explanation

The series is an arithmetic progression where each number should be 3 more than the previous one.
The sequence should follow the pattern: 24, (24+3=) 27, (27+3=) 30, (30+3=) 33, (33+3=) 36.
The number 31 breaks this pattern, as the difference between 27 and 31 is 4, not 3.
Alternatively, all other numbers in the series (24, 27, 33, 36) are multiples of 3. The number 31 is not a multiple of 3.

Option A: The number 24 is the correct starting point of the series. It fits the pattern of being a multiple of 3 (3 × 8).
Option B: The number 27 correctly follows 24 by adding 3 (24 + 3 = 27). It also fits the pattern of being a multiple of 3 (3 × 9).
Option D: The number 33 correctly follows the pattern if the preceding incorrect number (31) is replaced by the correct one (30). Then, 30 + 3 = 33. It is also a multiple of 3 (3 × 11).

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Identifying the incorrect term in a number series (Arithmetic Progression) as background academic context rather than a clinical decision trigger.
Logical reasoning and pattern recognition are foundational skills tested in many competitive and entrance exams.
While not directly clinical, the ability to identify deviations from a pattern is analogous to a nurse's skill in spotting an abnormal vital sign or a subtle change in a patient's condition that deviates from their baseline.
This skill is crucial for critical thinking and problem-solving in any professional field.

How to Approach the Question

First, examine the relationship between consecutive numbers in the series: 24, 27, 31, 33, 36.
Calculate the difference between each pair: 27-24 = 3; 31-27 = 4; 33-31 = 2; 36-33 = 3.
Observe the differences. The difference of '+3' appears most frequently, suggesting the underlying pattern is an arithmetic progression with a common difference of 3.
Hypothesize the correct series starting from 24 with a '+3' rule: 24, 27, 30, 33, 36.
Compare this correct series with the given series. The number 31 is in the place where 30 should be.
Therefore, 31 is the incorrect term that breaks the established pattern.

Concept Tested & Keywords

Concept Tested: Identifying the incorrect term in a number series (Arithmetic Progression)
Stem keywords: number series, wrong term, 24,27,31,33,36
Lead-in keywords: wrong term
Negative lead-in flag: false

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