A businessman bought 30 TV sets for ₹300000 in total. The average cost of 15 TV sets is ₹9000. What is the average cost of the remaining 15 TV sets?

Introduction / Context:
Averages with grouped data often need a total-first approach: compute the grand total, subtract the known subgroup total, and divide the remainder by the remaining count to get the second subgroup’s average.

Given Data / Assumptions:

• Total sets = 30; total cost = ₹300000.
• Average cost of first 15 sets = ₹9000 ⇒ subtotal known.
• Find average cost of remaining 15 sets.

Concept / Approach:
Let S1 be the cost of the first 15 and S2 the cost of the remaining 15. Then S1 = 15 * 9000. Since S1 + S2 = 300000, we get S2, and average for remaining = S2 / 15.

Step-by-Step Solution:

Verification / Alternative check:
Grand average is ₹300000 / 30 = ₹10000. With one subgroup below at ₹9000, the other must be above ₹10000 to balance to ₹10000 overall; ₹11000 satisfies this symmetry.

Why Other Options Are Wrong:

• ₹20000, ₹12000: Do not align with the computed remainder.
• ₹10000: That is the overall average, not the remaining subgroup’s mean.
• None of these: A correct value exists (₹11000).

Common Pitfalls:
Dividing the total by 15 or mixing up subgroup and overall averages.

Final Answer:
₹ 11000