The average age of a husband and his wife was 23 years at the time of their marriage. After five years they have a one-year-old child. What is the current average age of the family of three members?

Introduction / Context:
This problem tests your understanding of average age and how averages change when time passes and new members join a group. Questions involving families, children, and changes in average age are a staple of aptitude exams, because they check whether you can convert statements about averages into total sums of ages and then back into a new average.

Given Data / Assumptions:

• Initially, only the husband and wife are considered.
• Their average age at marriage is 23 years.
• After five years, both spouses are 5 years older.
• They now have a one-year-old child.
• We must find the present average age of the three family members.

Concept / Approach:
The key idea is that average = total sum of ages / number of persons. When time passes, every existing person's age increases by the same amount, so the total sum increases accordingly. When a new member is added, the total sum gets that person's age added and the number of persons increases by one. We work through totals instead of trying to manipulate averages directly.

Step-by-Step Solution:
At marriage, there are 2 people with average age 23 years.Total age then = 23 * 2 = 46 years.After five years, each of the two adults becomes 5 years older.Increase in total age due to time = 2 * 5 = 10 years.New total age of husband and wife = 46 + 10 = 56 years.They now have a child aged 1 year.Total age of all three family members = 56 + 1 = 57 years.Number of family members now = 3.Average age now = total age / number of members = 57 / 3 = 19 years.

Verification / Alternative check:
As a quick check, imagine the current ages. Let the husband and wife both have ages that average 28 years after five years, because 23 + 5 = 28. So together they total 56 years, and with a one-year-old child the total is 57 years. Dividing 57 by 3 again gives 19. This confirms that the calculation and reasoning are consistent.

Why Other Options Are Wrong:
Options like 25 or 23 years ignore the effect of adding the child or treat the situation as if only two people were still being averaged. Options 18 and 21 years are just approximate guesses without a proper sum-based calculation. Only 19 years fits the exact arithmetic derived from the given information.

Common Pitfalls:
Students often forget that the number of individuals changes from two to three and still divide by two. Others simply add 5 years to 23 and assume that is the new average without accounting for the child's much lower age. Always convert averages into totals, adjust for time and new members, and then convert back to an average.

Final Answer:
The current average age of the family is 19 years.