Mensuration Practice Test 8

Let length, breadth and height of the room be 3x, 2x and x respectively.
Area of the room = 2
[(l × h)+ (b × h)] = 2 [(3x × x)+ (2x × x)]
= 2(3x2+2x2)
= 10x2
New dimensions of room, i.e., length, breadth and height = 6x, x and

x

2

respectively.
New area of the room = 2 [(l × h) + (b × h)]
= 2[(6x×

x

2

)+(x×

x

2

)]
= 2[3x2+

x2

2

]
= 2(

7x2

2

) = 7x2
Percentage decrease in area =

3x2

10x2

×100 = 30 %