Chapter R.6, Problem 19E

In Exercises 17– 20, give the numbers in the exponential function to three decimal places.

Buying Power.

a. Find the exponential function that best fits the following data.

Years since 1980	Equivalent buying power of $100 (in 1980 dollars)
0	$100.00
10	$158.62
20	$208.98
30	$264.63
33	$282.85
(Source: http://data.bls.gov/cgi-bin/cpicalc.pl.)

b. Graph the scatterplot and the function on the same set of axes.

c. Use the function to estimate the equivalent buying power of S100 (in 1980 dollars) in 2020.

d. What other models also fit this data? Which model best predicts the equivalent buying power of $100 (in 1980 dollars) for future years? Why?