Construction company has four big front-end loaders located at four different workshops. The loaders must be moved to four different construction sites. The distances in kilometers are

tabulated below.

Loader A B C D Total distance

1 90 75 75 80 320

2 35 85 55 65 240

3 125 95 90 105 415

4 45 110 95 115 365

Total distance 295 365 315 365

Site

(a) How should the loaders be moved in order to minimize the total distance travelled? [6]

(b) Formulate the linear programming model for the data provided. [6]

(c) Formulate the dual model for the primal in (b). [6]

(d) Use the North-West Corner method to solve the problem. ​