Reconsider Prob. $8\mathrm{.}1\mathrm{.}7.$ Now assume that distribution centers $1,2,$ and $3$ must receive

exactly $10,20,$ and $30$ units per week, respectively. For administrative convenience,

management has decided that each distribution center will be supplied totally by

a single plant, so that one plant will supply one distribution center and the other

plant will supply the other two distribution centers. The choice of these assignments

of plants to distribution centers is to be made solely on the basis of minimizing total

shipping cost.