Final answer:
Supply quantities for nodes in a transshipment problem are represented by positive values. Negative values are used for demand at nodes. Understanding how supply and demand are represented on graphs helps identify shifts due to supply determinants such as costs and technology changes.
Step-by-step explanation:
In a transshipment problem, supply quantities for nodes are customarily indicated by positive values. These positive values represent the amount of goods supplied at each node. Conversely, negative values typically indicate the demand quantities at nodes, representing the amount of goods required.
When solving such problems one might encounter equations or inequalities where certain values can result in physically impossible solutions. In these cases, we discard said values, leaving only the possible values that make sense within the context of the problem. An example of this occurs when analyzing the concentration of a substance in a solution where one value of x might result in a negative concentration, which physically cannot be the case.
Understanding the depiction of supply and demand on graphs, helps grasp how the equations for Qd (quantity demanded) and Qs (quantity supplied) interact. Shifts in the supply curve, which are visual representations of the entire supply, can occur due to various supply determinants, such as input costs or technological advancements, and these shifts are graphically represented as movements to the left or right.