16. Researchers at a National Weather Center in the northeastern United States recorded the number of 90 days each year since records first started in 1875.  The numbers form a normal shaped distribution with a mean of u = 9.6 and a standard deviation of o = 1.9. To see if the data showed and evidence of global warming, they also computed the mean number of 90 days for the most recent n = 4 years and obtained M = 12.25.  Do the data indicate that the past four years have had significantly more 90 days than would be expected for a random sample from this population?  Use a one-tailed test with a = .05. (Show how all your work)