Room dimensions l, b, h — perimeter of ceiling vs area of walls (percentage): Let a room have length l, breadth b, and height h. Express the perimeter of the ceiling as a percentage of the total area of the four walls.

Introduction / Context:
This is a ratio/percentage problem connecting linear measure (perimeter of the rectangle l × b) to area measure (four walls area), requiring careful unit handling.

Given Data / Assumptions:

• Ceiling (top face) is l × b.
• Perimeter of ceiling P_ceiling = 2(l + b).
• Area of four walls A_walls = perimeter of base × height = 2(l + b) * h.

Concept / Approach:
Percentage = (P_ceiling / A_walls) * 100.

Step-by-Step Solution:
P_ceiling / A_walls = [2(l + b)] / [2(l + b)h] = 1/hPercentage = (1/h) * 100 = 100/h %

Verification / Alternative check:
Dimensional check: perimeter over area yields 1/length; multiplying by 100 gives percent per unit height, consistent with 100/h %.

Why Other Options Are Wrong:
100h% inverts the relationship; h% and h/100% misuse units.

Common Pitfalls:
Forgetting that four wall area uses the base perimeter times h, not 2lh + 2bh directly (though algebraically equivalent).

Final Answer:
100/h%