The expected weight of a child at the age of 8 years is?

Appeared in: KPSC Staff Nurse - 2021

Explanation

The expected weight of a child can be estimated using various age-based formulas, which are useful for quick assessments in a clinical setting.
For a child between 7 and 12 years, one formula used for calculation is: Weight (kg) = (Age in years × 7 + 5) / 2.
Applying this formula for an 8-year-old child: (8 × 7 + 5) / 2 = (56 + 5) / 2 = 61 / 2 = 30.5 kg.
This calculated weight directly matches one of the provided options.

Option A: This value is too low for an 8-year-old child. It would be closer to the expected weight of a 6-year-old if using the formula (Age × 2) + 8, which would yield 20 kg.
Option B: This value is incorrect and does not result from the application of the specified formula. A more common formula for this age, (Age × 7 - 5) / 2, would yield 25.5 kg, which is also not this value.
Option D: This value is too high for an 8-year-old according to the formula. This weight would be more typical for a child around 9 or 10 years of age.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Pediatric weight estimation using age-based formulas as background academic context rather than a clinical decision trigger.
Nurses use these formulas for a quick estimation of a child's expected weight, which is crucial for calculating medication dosages, assessing nutritional status, and monitoring growth.
A significant deviation from the expected weight can be an early indicator of underlying health issues like malnutrition, failure to thrive, or obesity, prompting further investigation with growth charts.
While formulas are useful for quick checks, plotting the child's weight on a standardized growth chart (like those from WHO or IAP) provides a more accurate assessment of their growth trajectory over time.

How to Approach the Question

First, identify the key information in the question: the child's age is 8 years.
Second, recall the various formulas used to estimate a child's weight. For the school-age period (7-12 years), one formula is (Age × 7 + 5) / 2.
Third, substitute the child's age into the formula: (8 × 7 + 5) / 2.
Fourth, perform the calculation: (56 + 5) / 2 = 61 / 2 = 30.5.
Finally, match the calculated weight (30.5 kg) with the given options to find the correct answer.

Concept Tested & Keywords

Concept Tested: Pediatric weight estimation using age-based formulas.
Stem keywords: expected weight, child, 8 years
Lead-in keywords: BEST, MOST RELEVANT CLUE
Clinical cues: Age/sex group narrows the expected diagnosis, intervention, or normal reference range.

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E6 Ghai Essential Pediatrics(pp 26-904 of 913) p. 10-12

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