The Earth has been getting warmer. Most climate scientists agree that one important cause of the warming is the increase in atmospheric levels of carbon dioxide (CO2), a greenhouse gas. Here is part of a regression analysis of the mean annual CO2 concentration in the atmosphere, measured in parts per thousand (ppt), at the top of Mauna Loa in Hawaii and the mean annual air temperature over both land and sea across the globe, in degrees Celsius. The scatterplots and residuals plots indicated that the data were appropriate for inference and the response variable is Temp.

a) Write the equation of the regression line.
b) Find the value of the correlation. Is there evidence of an association between CO2 level and global temperature?
c) Find the t-value and P-value for the slope. Is there evidence of an association between CO2 level and global temperature? What do you know from the slope and t-test that you might not have known from the correlation?
d) Do you think predictions made by this regression will be very accurate? Explain.

Coeff 10.707 0.010 Variable Intercept C02 SE Coeff) 0.4810 0.0013 R-squared-67.8% s =0.0985 with 29-2=27 degrees of freedom