The length of the longest rod that can fit in a cubical room of 4 m side is?  Choose the correct choice from the following.
A) 6.978 m B) 6.928 m C) 6.829 m D) 6.248 m E) 6.982 m

Rationale: the length of the longest rod = 4 sq . root of 3 = 6.928 m answer : b
Answer: B