If 125 / 1.25 = 12.5 / x, then what is the value of x?

Appeared in: DSSSB - 29 August 2019 (Shift-1)

Explanation

The question presents a proportion: 125 / 1.25 = 12.5 / x.
First, simplify the left side of the equation: 125 divided by 1.25 equals 100.
The equation then becomes 100 = 12.5 / x.
To solve for x, you can rearrange the equation to x = 12.5 / 100.
Dividing 12.5 by 100 involves moving the decimal point two places to the left, which results in 0.125.

Option A: This value (0.0125) would be the result of incorrectly dividing 12.5 by 1000 instead of 100. This represents a decimal placement error.
Option B: This is the numerator on the right side of the equation. Choosing this answer indicates a failure to solve for x.
Option D: This is the denominator on the left side of the equation. Choosing this value suggests confusion about which variable to solve for.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Solving a mathematical proportion equation as background academic context rather than a clinical decision trigger.
The ability to solve proportions is a fundamental math skill required for safe and accurate medication dosage calculation in nursing.
This skill is the basis for the 'Ratio and Proportion' method, one of the primary techniques taught for calculating doses: (Dose on Hand / Volume) = (Dose Desired / x).
Patient Safety: A simple decimal error in this type of calculation can lead to a tenfold or hundredfold dosing error, which can have catastrophic consequences for the patient, especially with high-alert medications or in pediatric populations.

How to Approach the Question

First, identify that the question is asking you to solve a proportion (two equal fractions).
Recognize the structure: a/b = c/x, where x is the unknown you need to find.
The most straightforward approach is to first simplify the known fraction (125 / 1.25) to a single number.
Once simplified, you will have an equation like 'Number = 12.5 / x'.
Rearrange this simple algebraic equation to isolate x.
Perform the final division and be extremely careful with the placement of the decimal point in your answer.

Concept Tested & Keywords

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Practise the full DSSSB - 29 August 2019 (Shift-1)

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