Confidence votes 20.3K. There are two basic types of submarine screws. (Screw is the proper term here as propeller is applied to small craft.) One of the screws is built for silence, and the other is built for speed. Screws built for speed typically have fewer blades and the blades are wider to grab more water as the screw spins in the water.
Economic Definition of assumption. Defined. Term assumption Definition: An initial condition or statement that sets the stage for an analysis by abstracting from the real world. Assumptions are important to economic theories and economic analysis. Some assumptions are used to simplify a complex analysis into more easily manageable parts.
Economic Analysis. The application of data to a theory of how people produce, trade, and use goods and services. One may use both qualitative and quantitative tools in economic analysis. For example, given a theory of what causes unemployment, an economic analyst may take the data in an attempt to find its true causes and compare them to the original theory.