Choose the correct option from the given ones that will complete the series:

7, 19, 9, 18, 13, 15, 19, ?

Appeared in: AIIMS Bhopal NO - 2018 (Shift-1st)

Explanation

The given sequence is an alternating series, composed of two independent series in the odd and even positions.
The series at the even positions is 19, 18, 15, ?.
The pattern in this series is subtracting consecutive odd numbers: 19 - 1 = 18; 18 - 3 = 15.
Following this pattern, the next odd number to subtract is 5.
Therefore, the missing term is calculated as 15 - 5 = 10.

Option A: This would imply a subtraction of 1 from the previous term (15 - 1 = 14), which breaks the established pattern of subtracting increasing odd numbers (-1, -3, -5).
Option C: This would imply a subtraction of 3 (15 - 3 = 12), which repeats the previous subtraction amount and does not follow the sequence of consecutive odd numbers.
Option D: This would imply a subtraction of 4 (15 - 4 = 11). This breaks the pattern because 4 is an even number, and the established logic involves subtracting odd numbers.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Recognizing patterns in alternating number series as background academic context rather than a clinical decision trigger.
While not a clinical question, logical reasoning and pattern recognition are fundamental skills for nurses.
These skills are crucial for interpreting trends in patient vital signs, recognizing subtle changes in a patient's condition, and making quick, logical decisions in complex situations.
For example, a nurse must recognize the pattern in a patient's deteriorating Glasgow Coma Scale score to intervene promptly.

How to Approach the Question

First, examine the series for a single, simple pattern (e.g., adding or multiplying by the same number). Notice that no simple pattern fits all the numbers.
Suspect an alternating or mixed series. To test this, write out the terms at odd positions and even positions separately.
Odd positions: 7, 9, 13, 19.
Even positions: 19, 18, 15, ?.
Analyze each sub-series independently to find its unique pattern. For the odd series, the pattern is adding consecutive even numbers (+2, +4, +6).
For the even series, the pattern is subtracting consecutive odd numbers (-1, -3).

Concept Tested & Keywords

Q-QYRkV2zDgZhxT13Q5vQg

Practise the full AIIMS Bhopal NO - 2018 (Shift-1st)

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