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.
Loading the player... A: Positive economics is objective and fact based, while normative economics is subjective and value based. Positive economic statements do not have to be correct, but they must be able to be tested and proved or disproved. Normative economic statements are opinion based, so they cannot be proved or disproved. While this distinction seems simple, it is not always easy to differentiate between the positive and the normative. Many widely-accepted statements that people hold as fact are actually value based.