The length, breadth and height of a room are in the ratio 11:5:7. If the breadth is doubled, length is increased by 4 times while the height is halved. Then the total area of the 4 walls of the room will:
OPtion
1) Increase by 65.00%
2) Increase by 57.50%
3) Increase by 52.25%
4) Increase by 68.75%
5) Increase by 58.25%
6) Increase by 55.25%
7) Increase by 62.75%
8) Increase by 68.25%
9) Increase by 75.65%
10)None of these
Solution
l:b:h=11:5:7
Area of 4 walls = 2*(l+b)*h
Inital Area:
Let h=7x, b=5x and l=11x
Area of 4 walls = 2*(11x+5x)*7x = 224x^2
New dimensions when breadth is doubled, length is increased by 4 times and the height is halved
l1=44x
b1=10x
h1=3.5x
New Area
Area2= 2*(44x+10x)* 7x/2x = 378x^2
% Increase in area = (378 - 224)/224 = 68.75%