1) Variable Cost Those costs that do not change with the level of output. 2) Long Run A time period long enough for a rm to adjust their plant sizes and for new rms to enter the industry. 3) Economies of Scale As a plant is reduced in size, a number of factors will for a time lead to higher average costs of production. 4) Product Monopoly A product's ability to satisfy a large number of consumers at the same time. 5) Marginal Revenue The change in total revenue that results from selling one more unit of output. 6) Total Revenue The total amount the seller receives from the sale of a product in a particular time period. 7) Oligopoly Plant and equipment that are underused because rms are producing less than minimum ATC outputs 8 ) Excess Capacity The creation of new products and production methods destroys the market positions of rms committed to existing products and old ways of doing business. 9) Herndahl Index Measures a market dominated by a few large producers a homogeneous product. 10) Wage Rate The price paid per unit of labor services per hour of week. 11) Econommic Rent The price paid for land and natural resources that are completely xed in total supply. 12) Interest Rates Determines the income you will earn on savings or the interest a rm or person will pay to borrow money. 13) Craft Union A union model which limits members by restricting members to specic function,e.g. electrician. 14)Time Value of Money The concept that money remains constant over time. 15) Compound Interest The total interst that cumulates over time on money deposited or borrowed. 16) Pure Monopoly A single rm is the major producer of a proudct for which there aren't substitutes. 17) Price Leadership A single rm is the sole producer of a proudct for which there are no close substitutes. 18) Accounting Prot The total amount of Total Revenue less Total Expenses. 19) Insurable Risks The risk for which it is possible to buy insurance from an insurance company. 20) Creative Destruction All productws produced have a useful period of life and will be repalced within that life