The following table shows data for the cost of natural gas in Texas (in dollars per Million Litres) for x years since 1990.

Year X Prince in euros per Million Litres

1990 6.31

1991 6.14

1992 6.32

1993 6.75

1994 6.8

1995 6.34

1996 7.46

1997 8.12

1998 8.04

1999 8.25

2000 9.58

2001 11.28

2002 9.25

a.Use the calculator to obtain the linear regression line of best fit for the original prices; round to three decimal places.

b.In a brief sentence, interpret the slope in the context of the problem.

c.Predict the price in dollars per million Btu for the year 2010. Then calculate the residual for the year 2010 if the actual price in 2010 was $11.57 per million litres.

d.What is the correlation coefficient, rounded to two decimal places. Is the linear association between the variables "weak" or "strong"? How do you know?