GMATnavigator wrote:
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
(a) remain the same
(b) decrease by 13.64%
(c) decrease by 15%
(d) decrease by 18.75%
(e) decrease by 30%
Source: Gmat Cat By Nill (Peterson)
Given: The length, breadth and height of a room are in the ratio 3:2:1. The breadth and height are halved while the length is doubled.
Asked: Total area of the four walls of the room will
The length, breadth and height of a room are in the ratio 3:2:1.
Let The length, breadth and height of a room be 3x, 2x & x respectively
Total area of the four walls of the room = 2 (3x*x + 2x*x) = 10x^2
The breadth and height are halved while the length is doubled.
The length, breadth and height of a room change to 6x, x & x/2 respectively
Total area of the four walls of the room =\(2 (6x*x/2 + x*x/2) = 7x^2\)
Change in area of the four walls = (7-10)/10 = -3/10 (30% decrease)
IMO E