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 four walls of the room will
- remain the same
- decrease by 13.64%
- decrease by15%
- decrease by18.75%
- decrease by30%
Option 5: decrease by 30%
l:b:h = 3:2:1
We can say that l = 3k, b = 2k and h = k.
New length, breath and height will be 6k, k and k/2 respectively.
Old area of 4 walls will be 2h(l + b) = 2k(3k + 2k) = 2k(5k) = 10k2
new area will be 2(k/2)(6k + k) = k(7k) = 7k2
we see 30% decrease in the area