The table below gives the number of shares traded in billions on the New York Stock Exchange.

Year 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998

Shares 11.562 16.669 23.309 36.009 41.118 39.946 38.512 34.284 50.176 64.003

a. What is the appropriate model for this data set - linear, quadratic, cubic, or exponential?

b. Find the appropriate model for this data set. (Be sure to define the model completely.)

c. Use the model to predict the number of shares that will be traded in 2011.

d. Assuming your model is accurate, when will the number of shares traded reach 250 billion?