Complete the series........13,17,21,.....29? & x20;

AIIMS Manglagiri NO - 2019

Reasoning

Medium

Complete the series........13,17,21,.....29?

Appeared in: AIIMS Manglagiri NO - 2019

The series presented is a simple arithmetic progression, a sequence of numbers where the difference between consecutive terms is constant.
To find the pattern, calculate the difference between the given terms: 17 - 13 = 4, and 21 - 17 = 4.
The constant difference (or common difference) is +4.
To find the missing term, add 4 to the preceding term: 21 + 4 = 25.
The pattern is confirmed by checking the next step: 25 + 4 = 29, which matches the final term in the series.

Option A: The value 15 is less than the previous term (21), but the series is clearly increasing.
Option B: Choosing 23 would mean the difference is +2 (21 + 2 = 23), which breaks the consistent +4 pattern established by the other numbers in the series.
Option C: The value 12 is less than the previous term (21). An increasing series cannot have a term that is smaller than the one before it.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Number Series - Arithmetic Progression as background academic context rather than a clinical decision trigger.
While not a clinical question, this type of logical reasoning is a critical skill for nurses.
Nurses use pattern recognition to interpret trends in a patient's vital signs, notice subtle changes in their condition, and anticipate potential complications.
Skills in calculating sequences are also foundational for medication dosage calculations, especially for titrating drips or planning infusion schedules.

How to Approach the Question

First, carefully examine the sequence of numbers provided: 13, 17, 21, __, 29.
Next, determine the relationship between the consecutive numbers. Calculate the difference between the first two (17 - 13) and the next two (21 - 17).
Observe that the difference is a constant +4 in both cases. This identifies the pattern as an arithmetic progression.
Apply this rule to find the missing number. Add 4 to the number just before the blank space: 21 + 4 = 25.
To confirm your answer, apply the rule one more time to see if it results in the final number of the series: 25 + 4 = 29. It does, so the answer is correct.
Finally, select the option that matches your calculated result.

Concept Tested & Keywords

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