The sole objective in the above minimum cost problem is to supply the most units (preferably all units) of the demand nodes at minimum cost. How will changing the demand at Node 4 from the current 30 units to 20 units impact the total cost? Total cost will increase by a known amount. Total cost will increase, but by an unknown amount. Total cost will decrease, but by an unknown amount. Total cost will not change. Need more information to answer this question. None of the above. Total cost will decrease by a known amount