The average salary of A, B, and C is Rs. 10,000. Only A's average monthly expenditure is known to be Rs. 6000. What is the average savings of B and C together?

Introduction / Context:
Sometimes average problems do not supply enough information to isolate unknowns for a subgroup. Recognizing insufficiency is as important as computing a value when possible.

Given Data / Assumptions:

• Average salary of A, B, C = Rs. 10,000 ⇒ total salary = Rs. 30,000
• Only A's average expenditure is known: Rs. 6000
• Expenditures or savings of B and C are not provided.

Concept / Approach:
To compute the average savings of B and C, we need their incomes (known only in total with A) and their expenditures (unknown). Without at least the combined expenditure of B and C, infinitely many distributions satisfy the constraints, leading to different savings outcomes.

Step-by-Step Solution:

Verification / Alternative check:
Different choices of B and C expenditures produce different savings while respecting the given information. Hence no unique value exists.

Why Other Options Are Wrong:

• Rs. 5500, Rs. 4500, Rs. 4000: Each assumes extra information not provided.
• None of these: Insufficiency is explicitly captured by “can't be determined.”

Common Pitfalls:
Assuming B and C have the same expenditure as A or that the group average for expenditure is known; neither is given.

Final Answer:
can't be determined