Define work breakdown structure and briefly discuss its importance. Besides considering the following WBS information of hypothetical housing project, determine the cost of the project.

WBS Item	Item code	Estimated cost
House	1	?
Primary structure	1.1	6,000,000 Br
Electrical infrastructure	1.2	500,000 Br.
Plumbing infrastructure	1.3	400,000Br.
Inside wall development rough finish	1.4	1,000,000 Br.
Foundation development	1.1.1	3,000,000Br.
Exterior well development	1.1.2	1,200,000Br.
Roof development	1.1.3	1,800,000 Br.