Find the missing number in the following number series?

8.26, 6.84,__________,4.00, 2.58

Appeared in: DSSSB - 28 August 2019 (Shift-1)

Explanation

The question requires identifying the missing term in a numerical sequence.
The pattern is an arithmetic progression, where each term is found by subtracting a constant value from the previous term.
The difference between the first two terms (8.26 - 6.84) is 1.42.
The difference between the last two terms (4.00 - 2.58) is also 1.42, confirming the constant difference.
Subtracting 1.42 from the second term (6.84) gives the missing term: 6.84 - 1.42 = 5.42.

Option A: This value does not fit the established pattern. If 5.18 were the missing term, the difference would be 6.84 - 5.18 = 1.66, which is inconsistent with the series' common difference of 1.42.
Option B: This value does not fit the established pattern. If 5 were the missing term, the difference would be 6.84 - 5 = 1.84, which is inconsistent with the series' common difference of 1.42.
Option C: This value does not fit the established pattern. If 5.12 were the missing term, the difference would be 6.84 - 5.12 = 1.72, which is inconsistent with the series' common difference of 1.42.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Arithmetic Progression in Number Series as background academic context rather than a clinical decision trigger.
While not a clinical question, logical reasoning and pattern recognition are essential skills for nurses.
These skills are used in interpreting trends in vital signs, lab results, and patient symptoms over time to identify improvement or deterioration.
For example, recognizing a steady decrease in a patient's blood pressure over several hours requires the same pattern-finding skill.

How to Approach the Question

First, examine the given series to determine if it is increasing, decreasing, or alternating.
Calculate the difference (or ratio) between the consecutive terms provided to identify the underlying mathematical rule.
In this case, calculate the difference between 8.26 and 6.84, and also between 4.00 and 2.58.
Confirm that the difference is constant, which establishes the pattern as an arithmetic progression.
Apply this rule to the term just before the missing number to calculate its value.
Verify your answer by applying the rule one more time to see if it yields the next number in the series.

Concept Tested & Keywords

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Practise the full DSSSB - 28 August 2019 (Shift-1)

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