Concept:The value of a beam is proportional to the square of its length, so value
=k×(length)2. Compare the total value of the two broken pieces with the value of the original whole beam.
Explanation:Let the lengths of the two broken pieces be
4x and
9x.
Therefore, the length of the original beam before the accident is
4x+9x=13x.
Value of the original beam
=k(13x)2=169kx2.
Value of the first broken piece
=k(4x)2=16kx2.
Value of the second broken piece
=k(9x)2=81kx2.
So, total value of the two pieces after breakage
=16kx2+81kx2=97kx2.
Since
97kx2<169kx2, there is a loss.
Loss in value
=169kx2−97kx2=72kx2.
Loss percentage
=169kx272kx2​×100=42.60%.
Answer:There is a
42.60% loss, so the correct option is
B. 42.60% loss.