Question

The area of four walls of a hall is 320${{m}^{2}}$. The length and breadth of the hall is 12.5 m and 7.5 m respectively, find the height of the hall.
A. 32 m
B. 9 m
C. 3 m
D. 5 m
E. None of these

Answer 1

Hint: In the above question we will assume the height to be a variable and then we will calculate the area of four walls in terms of variable and equate them to the given area of the four walls.

Complete step-by-step answer:

We have been given that the length (l) and breadth (b) of the hall is 12.5 m and 7.5 m respectively.

Now , let us assume the height of the wall to be “h”.
So, the area of the four walls = \[2(l+b)\times h\].
\[\begin{align}
  & \Rightarrow 320=2(12.5+7.5)\times h \\
 & \Rightarrow 320=2\times 20\times h \\
 & \Rightarrow \dfrac{320}{40}=h \\
 & \Rightarrow h=8m \\
\end{align}\]

Hence, the height is equal to 8 m.

Therefore, the correct option of the above question is option E.

Note: Just be careful while doing calculation as there is a chance that you might make a mistake and you will get the incorrect answer of the question. Also remember the formula to find the area of a wall, its volume as it will help you a lot in these types of questions. Also take care of the units of the lengths. Make sure that all the lengths are taken in the same units.