The length (in m, correct to one decimal place) of the longest pole that can be fitted in a room of dimensions
`12m xx 6m xx 4m` is:

Options

A. `7.2`
B. `14.0`
C. `13.4`
D. `12.6`

Answer

To find the length of the longest pole that can be fitted in a room with dimensions 12m x 6m x 4m, we need to calculate the diagonal of the cuboid formed by these dimensions. The formula for the diagonal \(d\) of a cuboid is given by:

\[ d = \sqrt{L^2 + B^2 + H^2} \]

where \(L\) is the length, \(B\) is the breadth, and \(H\) is the height of the cuboid.

### Step-by-Step Solution:

1. **Identify the dimensions of the room:**
- Length \(L = 12\) m
- Breadth \(B = 6\) m
- Height \(H = 4\) m

2. **Substitute the dimensions into the diagonal formula:**
\[ d = \sqrt{12^2 + 6^2 + 4^2} \]

3. **Calculate each square:**
- \(12^2 = 144\)
- \(6^2 = 36\)
- \(4^2 = 16\)

4. **Add the squares together:**
\[ 144 + 36 + 16 = 196 \]

5. **Take the square root of the sum:**
\[ d = \sqrt{196} = 14 \]

6. **Final result:**
The length of the longest pole that can be fitted in the room is \(14\) m.

### Conclusion:
The length of the longest pole that can be fitted in the room is **14.0 m**.