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Q: The length, breadth and height of a room are in the ratio 7:3:1. If the breadth and height are doubled while the length is halved, then by what percent the total area of the 4 walls of the room will be increased  ?

  • 1
    90%
  • 2
    88%
  • 3
    85%
  • 4
    84%
  • Show Answer
  • Workspace

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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