A 16 years old male on IQ testing has a mental age of 9 years. He has:

Appeared in: BHU NO-2019

Explanation

The Intelligence Quotient (IQ) is calculated using the formula: IQ = (Mental Age / Chronological Age) × 100.
Given a mental age of 9 years and a chronological age of 16 years, the IQ is (9 / 16) × 100 = 56.25.
According to standard classifications (like ICD-10 or DSM-5), an IQ score between 50 and 70 is classified as Mild Intellectual Disability (or Mild Mental Retardation).
Since the calculated IQ is 56.25, the individual's condition is classified as mild mental retardation.

Option A: This is incorrect. Moderate mental retardation corresponds to an IQ range of 35–49. The calculated IQ of 56.25 is above this range.
Option B: This is incorrect. Severe mental retardation corresponds to an IQ range of 20–34. The calculated IQ of 56.25 is significantly higher.
Option C: This is incorrect. Profound mental retardation corresponds to an IQ below 20. The calculated IQ of 56.25 is well above this level.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Calculation of Intelligence Quotient (IQ) and classification of intellectual disability (mental retardation) as background academic context rather than a clinical decision trigger.
Assessing IQ is a fundamental step in diagnosing intellectual disability. This diagnosis is crucial for developing appropriate educational plans, vocational training, and support systems tailored to the individual's abilities.
Nurses often play a key role in identifying developmental delays during routine check-ups, supporting families through the diagnostic process, and collaborating with multidisciplinary teams to create holistic care plans.
What if? If the mental age was 6 years instead of 9, the IQ would be (6/16) * 100 = 37.5. This would shift the classification to Moderate mental retardation, indicating a need for a higher level of support and supervision in daily life and learning.

How to Approach the Question

First, recall the standard formula for calculating the Intelligence Quotient (IQ): IQ = (Mental Age / Chronological Age) × 100.
Next, identify the values provided in the question: Mental Age (MA) = 9 years and Chronological Age (CA) = 16 years.
Substitute these values into the formula: IQ = (9 / 16) × 100.
Perform the calculation to find the IQ score: 0.5625 × 100 = 56.25.
Finally, compare the calculated IQ score to the standard classification ranges for mental retardation to determine the correct category (e.g., Mild, Moderate, Severe, Profound).

Concept Tested & Keywords

Concept Tested: Calculation of Intelligence Quotient (IQ) and classification of intellectual disability (mental retardation).
Stem keywords: IQ testing, mental age, chronological age
Lead-in keywords: BEST, MOST RELEVANT CLUE
Clinical cues: Chronological Age: 16 years
Clinical cues: Mental Age: 9 years

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E6 Parks TextBook of Preventive & Social Medicine part 2 — Subpart A (pp 1-232 of 464) pp. 216-218, 82-84

Practise the full BHU NO-2019

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