Mathematical modeling

These assumptions are quite restrictive. We will see, however, that clever modeling canhandle situations that may appear to violate these assumptions. The next assumption isthe Divisibility Assumption: it is possible to take any fraction of any variable. Rethinkingthe Marketing example, what does it mean to purchase 2.67 television ads? It may be thatthe divisibility assumption is violated in this example. Or, it may be that the units aresuch that 2.67 “ads" actually corresponds to 2666.7 minutes of ads, in which case we can“round off" our solution to 2667 minutes with little doubt that we are getting an optimalor nearly optimal solution.The final assumption is the Certainty Assumption: linear programming allows for nouncertainty about the numbers. An ad will reach the given number of people; the numberof assembly hours we give will certainly be available. It is very rare that a problem willmeet all of the assumptions exactly. That does not negate the usefulness of a model. Amodel can still give useful managerial insight even if reality differs slightly from therigorous requirements of the model. For instance, the knowledge that our chip inventoryis more than sufficient holds in our first model even if the proportionality assumptions arenot satisfied completely.2.7 Linear Programming ModelsLinear programming models are found in almost every field of business. The next subsectionsshow a number of problems and how to model them by the appropriate choice ofdecision variables, objective, and constraints.2.7.1 Diet ProblemProblem DefinitionWhat is the perfect diet? An ideal diet would meet or exceed basic nutritionalrequirements, be inexpensive, have variety, and be “pleasing to the palate". How can wefind such a diet? Suppose the available foods are as follows:Systems Analysis 33 Dr. Emad Elbeltagi