KBSZ-AM

I need some help with my economics review for my final.?

I have the basic answers for almost all of these, but the answers are supposed to be alot more detailed than what I can come up with; please help me!

1.)Why are the issues of scarcity and choice the basis of economics?
2.)Why does every decision a person makes involve the trade offs and opportunity costs?
3.)What are the three key economic questions every society must answer?
4.) What are the advantages of a free market?
5.)What elements of a centrally planned economy are found in a mixed economy?
6.)Explain the concept of "invisible hand" in relation to economics.
7.)What are the benefits of the American Free Enterprise system?
8.)How does the government help promote stability and growth in the American Free Enterprise system?
9.)Why is it necessary for the government to create public goods?
10.)How does the substitution effect and the income effect influence the decisions of consumers?
11.)What factors can cause a shift in the demand curve, rather than movement along the curve?
12.)Why is it that some products have a very elastic demand and other do not?
13.)What costs must a producer consider in determining the rpice they will charge for an item they produce?
14.)What factors can cause a shift in the supply curce, rather than movement along the curve?
15.)How do businesses determine their profit?

If you have an economics textbook, you should look up some of these ideas and terms in the index. Otherwise, there are some helpful links below that will help you find some of the more hidden ones. I hope it helps.