Answer : 1 90% Explanation : Answer: A) 90% Explanation: Let length, breadth and height of the room be 7, 3, 1 unit respectively. Area of walls = 2(l b)xh = 2(7 3)x1 = 20 sq. unit. Now, length, breadth and height of room will become 3.5, 6 and 2 respectively. Area of walls = 2(l b)xh = 2(3.5 6)x2 = 38 sq. unit. % Increase in the area of walls = (38-20)x100/20 = 90%.

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