Formula used for converting Celsius scale of temperature to Fahrenheit scale?

Appeared in: KPSC Staff Nurse - 2018

Explanation

The correct formula to convert temperature from Celsius (°C) to Fahrenheit (°F) is F = (C × 9/5) + 32.
This formula works by first scaling the Celsius temperature (multiplying by 9/5 or 1.8) to account for the different degree sizes between the scales.
Then, it adds 32 to adjust for the offset in the freezing points (0°C is equivalent to 32°F).
Using a known value like the freezing point of water (0°C), the formula correctly gives (0 × 9/5) + 32 = 32°F.

Option B: This option uses an incorrect fraction (5/9) and an incorrect mathematical operation (subtraction of C). It does not follow the principles of scale conversion.
Option C: This option presents a mathematically nonsensical format. Dividing 9/5 by 32 and then subtracting C does not correspond to any physical or mathematical conversion formula.
Option D: This option incorrectly applies parts of the Fahrenheit to Celsius conversion formula. The correct formula is C = (F - 32) × 5/9. This option uses the wrong order of operations and the wrong starting scale.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Temperature Conversion: Celsius to Fahrenheit as background academic context rather than a clinical decision trigger.
Nurses must be proficient in converting temperatures as different healthcare facilities may use different scales. Patient education often requires converting Celsius to Fahrenheit, as it is more commonly used by the general public in some regions.
Accurate temperature conversion is crucial for correctly identifying fever (pyrexia) and hypothermia, which guides clinical interventions like administering antipyretics or initiating warming measures.
A temperature of 38°C is considered a fever, which converts to 100.4°F. Miscalculation could lead to either overlooking a fever or treating a normal temperature unnecessarily.

How to Approach the Question

Identify that the question asks for a specific, standard scientific formula.
Recall the relationship between the Celsius and Fahrenheit scales. Key points to remember are the freezing point (0°C = 32°F) and boiling point (100°C = 212°F) of water.
Use a known reference point to test the options. The easiest is the freezing point, C=0.
Substitute C=0 into the first option: F = (9/5 × 0) + 32 = 32. This matches the known freezing point in Fahrenheit, confirming it is the correct formula.
Quickly check the other options with C=0 to see they are incorrect. For example, option D gives F = (5/9 × 0) - 32 = -32, which is wrong.

Concept Tested & Keywords

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E6 Nursing Fundamentals Taylor p. 120-122

Practise the full KPSC Staff Nurse - 2018

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