Walls papering cost scaling — Papering four walls of a room costs ₹ 48. In another room, each of length, breadth, and height is doubled. Find the new papering cost.

Introduction / Context:Area of the four walls (ignoring ceiling and floor) is the lateral surface area = perimeter * height = 2(L + B) * H. If all three linear dimensions double, both perimeter and height double, so the wall area scales by a factor of 4.

Given Data / Assumptions:

• Original cost ∝ wall area = 2(L + B) * H
• New dimensions: 2L, 2B, 2H

Concept / Approach:New wall area = 2(2L + 2B) * (2H) = 4 * [2(L + B) * H] = 4 × original wall area. Cost scales linearly with area.

Step-by-Step Solution:New cost = 4 * ₹ 48 = ₹ 192

Verification / Alternative check:Proportionality between area and cost is a standard assumption in such problems.

Why Other Options Are Wrong:384 corresponds to factor 8 (incorrect); 96 is factor 2; 298 and 240 are arbitrary.

Common Pitfalls:Forgetting that doubling L and B doubles the perimeter; then doubling height multiplies by another 2.

Final Answer:Rs. 192