Global warming, Part II: Let's consider the differences between the temperature readings on January 1 of 1968 and 2008 at 51 locations in the continental US. The mean and standard deviation of the reported differences are 1.1 degrees and 4.9 degrees respectively. a) Calculate a 90% confidence interval for the average difference between the temperature measurements between 1968 and 2008. Round your answers to 2 decimal places. lower bound: degrees upper bound: degrees b) Interpret this interval in context. We are 90% confident that 90% of the time the differences in temperatures from year to year will be between the lower bound and upper bound We are 90% confident that the true mean difference in temperatures is contained between the lower bound and upper bound We are 90% confident that the mean difference in these sample temperatures is contained between the lower bound and upper bound There is a 90% chance that the difference in temperatures in a city from year to year will be between the lower bound and upper bound c) Does the confidence interval provide convincing evidence that the temperature was higher in 2008 than in 1968 in the continental US