Q.71 Consider the following statements with respect to long wall-short wall method. Which of the following statement is/are correct? I. The wall that is taken first is treated as the length, though the length may be lesser. II. The wall with longer length has to be taken as the long wall.
- ABoth statements I and II are false
- BOnly statement II is true
- COnly statement I is trueCorrect
- DBoth statements I and II are true
Solution
Concept
In the long wall-short wall method, the walls of one direction (taken first) are called long walls and are measured out-to-out. The walls of the other direction are short walls, measured in-to-in. The long wall need not be the longer one.
Formula
Long wall length (c/c) + one breadth = out-to-out length Short wall length (c/c) - one breadth = in-to-in length
Step-by-step solution
1. In this method, walls are split into two groups: long walls and short walls. 2. The walls taken first in one direction are called long walls. They are measured out-to-out. 3. The walls in the other direction are short walls. They are measured in-to-in. 4. The name 'long wall' is only a convention. The wall taken first is treated as the long wall even if its actual length is smaller. 5. So Statement I is true and Statement II is false. Answer is (C).
Explanation
In the long wall-short wall method, the walls you take first are called long walls and measured out-to-out. The actual length does not matter, so a shorter wall can also be the long wall. Statement I is correct and Statement II is wrong.
Why the other options are wrong
A: Statement I is true, so 'both false' is wrong. B: Statement II is false, because the long wall need not be the longer wall. D: Both cannot be true, because Statement II is false.
Shortcut
Long wall = the wall taken first (out-to-out). It is not the wall with the larger length.
Common mistake
Thinking the 'long wall' must always be the physically longer wall.
Correct answer: C) Only statement I is true