#4) Commuter ridership in Athens, Greece, during the summer months is believed to be heavily tied to the number of tourists visiting the city. During the past 12 years, the data are given in the following table.

Year	Number of Tourists (millions)	Ridership (hundreds of thousands)
1	6	11
2	11	16
3	8	16
4	10	14
5	19	28
6	18	26
7	16	21
8	20	25
9	24	45
10	18	28
11	11	18
12	19	35

a) Create time series plot for the ridership.

b) Using linear regression to see if using the year is a good predictor for the ridership. What is the regression equation? How accurate is the model?

c) Using linear regression to see if using the number of tourists is a good predictor for the ridership. What is the regression equation? How accurate is the model?

d) Which linear regression equation is better? What is the expected ridership if 10 million tourists visit the city next year?