Aptitude - Volume and Surface Area - Discussion

Thanks @Lokesh.

I cannot understand this! Please, anyone explain it.

Why isn't an area of four walls equal to 4*l*b?

Thank you for explaining the answer in well and suitable form @Lokesh.

@Erika,

Here four walls does not include the floor and the ceiling which is the top floor. Out of the four walls, sum of the areas of 2 walls which are opposite to each other is length* height+ length*height= 2*length*height.

Similarly, the sum of the areas of the 2 remaining two walls which are opposite to each other is breadth*height+breadth*height=2* breadth*height. So, the sum of areas of 4 walls= 2lh+2bh=2h (l+b). While calculating the area of a wall must consider the height of the wall.

Floor Area = 15 x 12 = 180 m.
Ceiling Area = 15 x 12 = 180 m.

Sum of Floor & Ceiling Area = 180 + 180 m = 360 m
- now,in the question "f the sum of the areas of the floor and the ceiling is equal to the sum of the areas of four walls." it means ,
360+360 = 720.

Please, help me to get it.

Thanks. @Sonu.

Simple formula,

h= (l * b) / (l + b) thus,
h= (15 x 12) / (15 + 12)
h= (180) / (27),
h= 180/27.

Volume of rectangle = l * b * h
= 15 x 12 x 180/27,
= 1200 cubic meter.

Thanks @Sonu.

Thanks for the answer @Jay R.