An opportunity cost is the cost of an alternative that must be forgone in order to pursue a certain action. In other words, the cost of enjoying more of one good in terms of sacrificing the benefit of another good is termed as opportunity cost of the additional unit of the good.
Example: We have Rs 15,000 with two choices a) to invest in the shares of a company XYZ or b) to make a fixed deposit which gives interest 9%. If the company XYZ gives a return of 15%, we will benefit when we invest in the shares as the alternative would be less profitable. However if company’s return is only 3% when we could have made a return of 9% from FD, then our opportunity cost is (9% - 3% = 6%).

The production possibilities curve (PPC) is a graph that shows all of the different combinations of output that can be produced given current resources and technology. Sometimes called the production possibilities frontier (PPF), the PPC illustrates scarcity and tradeoffs.  The PPF is extremely important in describing a range of economic phenomena. The PPF can be used to explain the concept of opportunity cost: Rather than measuring costs in dollars which are rather arbitrary (and change with inflation), we can measure the cost of producing one good in terms of not producing other goods.

Accountancy is the practice of recording, classifying, and reporting on business transactions for a business. It provides feedback to management regarding the financial results and status of an organization. 

Advantage of accounting :

- Comparison of financial of financial results with other firms. (iii) Helps in decision making by providing relevant information. (v) Providing information to interest parties and user. (vi) Accounting record business records in systematic manner.

The quantity demanded (qD) is a function of five factors—price, buyer income, the price of related goods, consumer tastes, and any consumer expectations of future supply and price. The law of demand states that, if all other factors remain equal, the higher the price of a good, the less people will demand that good. ... This means that the higher the price, the higher the quantity supplied. Producers supply more at a higher price because selling a higher quantity at a higher price increases revenue.  The demand for a good depends on several factors, such as price of the good, perceived quality, advertising, income, confidence of consumers and changes in taste and fashion. ... It shows the quantity of a good consumers plan to buy at different prices

A centrally planned economy is an economy where decisions on what to produce, how to produce and for whom are taken by the government in a centrally managed bureaucracy. Central planning is also referred to as a 'Command economy' or 'Communist economy.

Micro economic problems. One of the most frequent problems is that economic decisions can have external effects on other people not involved in the transaction. For example, if you produce power from coal, the pollution affects people all over the world (acid rain, global warming).

The Marginal Rate of Substitution can be defined as the rate at which a consumer is willing to forgo a number of units good X for one more of good Y at the same utility. The Marginal Rate of Substitution is used to analyze the indifference curve. 

In plural sense, it means a systematic collection of numerical facts and in singular sense; it is the science of collecting, classifying and using statistics.

 In the Plural Sense: “Statistics are numerical statements of facts in any department of enquiry placed in relation to each other.

Microeconomics is the study of decisions made by people and businesses regarding the allocation of resources and prices of goods and services. The government decides the regulation for taxes. Microeconomics focuses on the supply, that determines the price level of the economy. It uses the bottom-up approach strategy to analyze the economy. In other words, microeconomics tries to understand human choices and resource allocation. Microeconomics does not decide what are the changes taking place in the market, instead, it explains why there are changes happening in the market.

the important key factors of microeconomics are :

• Demand, Supply, and Equilibrium
• Production Theory
• Costs of Production
• Labor Economics

Statistics refers to the aggregates or averages that relate to an enquiry or some relationship. Such aggregates facilitate the presentation of data in a simplified manner. Besides presentation, statistics also enable a reader to make comparison among two or more variables. On the contrary to this, statistics also involve some limitations which often lead to the situation of distrust on statistics and its methods. Such limitations evoked ‘Mark Twain’ of U.S. to introduce a phrase called ‘Lies, Damned lies and Statistics’. This phrase was introduced to highlight the shortcomings (limitations) associated with statistics.

Statistics is the science of collecting,representing and analysis of data.For example : Census of India is a statistical activity. Census is carried every 10 years and it involves collection of data,by going in to each house and registering their names etc.It also involver compiling and presentation of data. Ultimately,the concerned officials analyze the trend of composition and quantity of population.