The average age of a husband and wife is 23 years at the beginning of their marriage. After five years they have a one year old child. The average age of the family of three, when their child was born is :

1. A

   23 years

2. B

   18 years

3. C

   24 years

4. D

   20 years

Appeared in: RRB Staff Nurse Delhi-2015

Explanation

• The initial total age of the couple at marriage is the average age multiplied by the number of people: 23 years × 2 = 46 years.
• The question asks for the average age when the child was born. Since the child is 1 year old after 5 years of marriage, the child was born 4 years after the marriage (5 - 1 = 4).
• After 4 years, both the husband and wife have aged by 4 years. Their new total age is the initial total age plus the additional years: 46 + (4 × 2) = 54 years.
• At the moment of birth, the family consists of three members: the husband, the wife, and the child (age 0).
• The total age of the family is the sum of the parents' ages plus the child's age: 54 + 0 = 54 years.
• The average age of the family is the total age divided by the number of family members: 54 / 3 = 18 years.

Why Other Options Were Wrong

• Option A: This is the average age of the couple at the time of their marriage. It does not account for the passage of time or the addition of the child to the family.
• Option C: This is a calculation error. It might result from incorrectly using 5 years of aging for the parents (46 + 10 = 56) and then rounding the result of 56/3, or another miscalculation.
• Option D: This is a calculation error. It might be obtained by incorrectly calculating the total age or the number of family members. For example, (46+4)/2.5 is 20, but this logic is flawed.

Related Visual

• Visual 1: Flowchart - A flowchart illustrating the step-by-step calculation: 1. Calculate initial total age. 2. Determine the time elapsed until birth. 3. Calculate the new total age of parents. 4. Add the child's age (0). 5. Divide by the new family size (3).

Clinical Relevance

• Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Calculating average age with changing group size and time progression as background academic context rather than a clinical decision trigger.
• This question tests basic mathematical aptitude and logical reasoning, which are foundational skills for nursing students and professionals.
• While not a clinical question, the ability to perform accurate calculations is critical in nursing for tasks like medication dosage calculation, IV drip rate monitoring, and interpreting patient data.
• What if? If the child was 2 years old after five years of marriage, the calculation would change. The birth would have occurred 3 years after marriage. The parents' total age would be 46 + (3*2) = 52. The family average would be 52 / 3 = 17.33 years.

How to Approach the Question

• First, identify the initial information provided: the number of individuals (2: husband and wife) and their average age (23 years).
• Calculate the total sum of their ages at the starting point: 23 years/person × 2 people = 46 years.
• Carefully read the timeline. The key is that after 5 years, the child is 1 year old. This means the birth happened 4 years after the marriage, not 5.
• Update the total age of the original members to this new point in time. Add 4 years for the husband and 4 years for the wife to the initial total: 46 + 4 + 4 = 54 years.
• Account for the new family member. At the moment of birth, the child's age is 0. The family size is now 3.
• Calculate the final average age by dividing the new total age by the new number of family members: (54 + 0) / 3 = 18 years.

Concept Tested & Keywords

• Concept Tested: Calculating average age with changing group size and time progression.
• Stem keywords: average age, husband and wife, five years, one year old child
• Lead-in keywords: average age of the family
• Clinical cues: Age/sex group narrows the expected diagnosis, intervention, or normal reference range.

Question ID

Q_05ONezlmzLvoL_pLIeTX

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