What will be the next number: 17, 12, 6, -1?

Appeared in: SGPGI Nursing Officer-2022

Explanation

The question requires finding the next term in the numerical sequence: 17, 12, 6, -1.
To identify the pattern, calculate the difference between consecutive terms: 12 - 17 = -5; 6 - 12 = -6; -1 - 6 = -7.
The differences form a simple arithmetic progression: -5, -6, -7. The next logical difference in this pattern is -8.
Applying this difference to the last term of the sequence gives the next term: -1 + (-8) = -9.

Option A: Choosing -6 would imply a difference of -5 from the last term (-1 - (-6) = 5), which does not follow the established pattern of decreasing by one each time (-5, -6, -7).
Option C: Choosing -5 would imply a difference of -4 from the last term (-1 - (-5) = 4), breaking the consistent pattern of subtracting an incrementally larger integer.
Option D: Choosing -7 would imply a difference of -6 from the last term (-1 - (-7) = 6), which repeats a previous difference instead of continuing the clear progression.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Number Series Pattern Recognition as background academic context rather than a clinical decision trigger.
This type of logical reasoning question assesses problem-solving and analytical skills, which are crucial for nurses in all clinical settings.
Nurses use pattern recognition daily when monitoring vital signs, interpreting lab results, or identifying trends in a patient's condition over time.
What if the sequence represented a patient's Glasgow Coma Scale (GCS) score at different time intervals, showing a decline? Recognizing this deteriorating pattern is critical for escalating care promptly.

How to Approach the Question

First, carefully examine the given sequence of numbers: 17, 12, 6, -1.
Calculate the difference between the first and second numbers (12 - 17 = -5).
Continue calculating the difference for all subsequent pairs of numbers (6 - 12 = -6, and -1 - 6 = -7).
Analyze the sequence of differences you've calculated (-5, -6, -7) to identify the underlying rule. Here, the number being subtracted increases by 1 each time.
Extrapolate the pattern to find the next difference, which would be -8.
Apply this next difference to the last number in the original sequence (-1 - 8) to find the final answer, which is -9.

Concept Tested & Keywords

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Practise the full SGPGI Nursing Officer-2022

Attempt every question from this paper in a timed mock, then review the full solution for each one.