11.  The theory always came first, put forward from the desire to have an elegant and consistent mathematical model.

12.  This is a mathematical model designed to determine the optimal amount of inventory that a firm should carry.

13.  Make a mathematical model, in the form of a diagram, of this information and use it to determine the shortest and longest possible flight times.

14.  The kinetic theory of gases is a mathematical model of an ideal gas.

15.  Some will involve drawing instruments, some real life calculations, and some simple mathematical model making -- which is another term for algebra.

16.  As eagerly as he constructed mathematical models, colleagues and former students said, Durand used the results as an aid to judgment rather than the final answer.

17.  Aspen, based in Cambridge, Mass., creates software that helps chemical engineers develop mathematical models of manufacturing processes.

18.  At issue is the mathematical model that the group used, said Melissa Skolfield, assistant secretary for public affairs at the Department of Health and Human Services.

19.  At first he depended on the use of mathematical models of disorder.

20.  At the college, he developed a formula for calculating the exchange of oxygen into streams and rivers that provided a mathematical model for explaining the process.