a. Steps to create a scatter plot to identify the best model by using a graphing utility.

1. Set corresponds to the year 1900 so that corresponds to the year 1920

2. Set the window of the scatter plot as

3. Use table graph feature and enter the corresponding tabular values as shown below: Here denote the number of years after 1900 and denote the price of all goods and services for urban households, based on a price of $1 for them in 1913

20	2.02	70	3.92
25	1.77	75	5.43
30	1.69	80	8.32
35	1.38	85	10.87
40	1.41	90	13.20
45	1.82	95	15.39
50	2.43	100	17.39
55	2.71	105	19.73
60	2.99	106	20.18
65	3.18