9. Model building is a central element in operations research method. Give a description of the following basic types of models: (

a) iconic,

(b) analogue, and (

c) mathematical (symbolic), with particular reference to the special insights provided by each.

Give an account of the information requirements, assumptions and applications of any three of the following different type of mathematical models:

(a) allocation,

(b) queuing,

(c) inventory,

(d) replacement.