The length, breadth and height of a room are in the ratio 3:2:1. If the breadth and height are halved, while the length is doubled. Then the total area of the 4 walls of the room will be decreased by
option
a) 30%
b) 18.75%
c) 15%
d) 13.6%

• l:b:h=3:2:1
  let
  h=x
  b=2x
  l=3x
  area = 2*(l+b)*h
  area1= 2*(3x+2x)*x = 10x^2
  
  
  l2=6x
  b2=x
  h2=x/2
  area2= 2*(6x+x)*x/2 = 7x^2
  
  %decrease= (10x2 - 7x2)/(10x2)*100 = 30%
• 10 years agoHelpfull: Yes(53) No(8)
• Area of 4 walls of a room=2*(l+b)*have
  2* (3+2)*1=10
  New, 2*(6+1)*1/2=7
  % decrease = difference between original and new/original×100
  %decrease =3/10×100
  30%
• 5 years agoHelpfull: Yes(7) No(1)
• the correct answer is 13.6%
  as surface area of l:b:h when 3:2:1 is 22
  and area when l:b:h is 6:1:1/2 is 19
  so,((22-19)/22)*100 = 13.6%
• 10 years agoHelpfull: Yes(6) No(21)
• original area of 4 walls is 2(3x^2+2x^2)=10x^2
  and new area of 4 walls is 2(3x^2+x^2/2)=7x^2
  so decrease in area is 30%
• 10 years agoHelpfull: Yes(4) No(2)
• thank u @ ANCHAL
• 10 years agoHelpfull: Yes(2) No(6)
• percentage change in total area of 4 walls of the room is asked MILLS
• 10 years agoHelpfull: Yes(1) No(1)
• 33.33
  1/3
  
• 10 years agoHelpfull: Yes(0) No(0)