DIRECTIONS: Select the related numbers from the given alternatives.

21:3 :: 574 : ?

Appeared in: DHS 2018 shift 1st

Explanation

The problem presents a number analogy where the relationship between the first pair of numbers must be applied to the second pair.
The logic connecting the first pair (21 and 3) is that the second number is obtained by dividing the first number by 7 (21 ÷ 7 = 3).
Applying this same logic to the second number (574), we divide it by 7.
The calculation is 574 ÷ 7 = 82.
Therefore, 82 is the number that correctly completes the analogy.

Option A: This option does not follow the established mathematical rule. 574 divided by 7 equals 82, not 23.
Option C: This is an incorrect calculation. Applying the rule of dividing by 7 to 574 yields 82, not 97.
Option D: This option results from a miscalculation. 574 divided by 7 is 82, not 113.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Number Analogy as background academic context rather than a clinical decision trigger.
This question assesses logical reasoning and numerical ability, which are foundational skills for nurses.
Nurses use similar logical deduction for tasks like calculating drug dosages, interpreting lab results, and identifying patterns in a patient's vital signs.
For example, if a medication is dosed at 2mg/kg, a nurse must apply a consistent rule (multiplication) to different patient weights, similar to applying the 'divide by 7' rule here.

How to Approach the Question

First, analyze the relationship between the first pair of numbers (21 and 3).
Consider common mathematical operations: addition, subtraction, multiplication, division, squares, cubes, or sum of digits.
In this case, you can get to 3 by dividing 21 by 7 (21 ÷ 7 = 3). Another possibility is summing the digits (2 + 1 = 3).
Test both potential rules on the second number (574).
Applying the division rule: 574 ÷ 7 = 82. This result (82) is one of the options.
Applying the sum of digits rule: 5 + 7 + 4 = 16. This result is not among the options.

Concept Tested & Keywords

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Practise the full DHS 2018 shift 1st

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