The average age of 7 members of Patel's family is 25 years today. What was the family's average age 3 years ago?

Introduction / Context:
Average age problems often rely on the idea that time shifts the sum of ages by a constant amount per person. Rolling the clock backward or forward changes totals linearly with the number of individuals.

Given Data / Assumptions:

• Current average age = 25 years
• Number of family members = 7
• We seek the average age 3 years earlier.

Concept / Approach:
If each of 7 people is 3 years younger when going back in time, the total age decreases by 7 * 3. Average = (total age) / 7; shifting totals by a multiple of 7 shifts the average by exactly that many years.

Step-by-Step Solution:

Verification / Alternative check:
Shortcut: Going back 3 years reduces the average by exactly 3 since all 7 members shift equally. 25 - 3 = 22, which matches the computed value.

Why Other Options Are Wrong:

• 21 year: Subtracts 4 instead of 3.
• 25 year: That is the current, not past, average.
• none of these: An exact correct option exists.
• 27 year: This would be the average 2 years in the future from today, not 3 years in the past.

Common Pitfalls:
Applying the 3-year shift to only one person or miscomputing the total decrease (forgetting to multiply by the number of members).

Final Answer:
22 year