Question: LA rainfall. The Los Angeles Almanac Web site reports recent annual rainfall (in inches), as shown in the table.
a) Create a 90% confidence interval for the mean annual rainfall in LA.
b) If you wanted to estimate the mean annual rainfall with a margin of error of only 2 inches, how many years' data would you need?
c) Do these data suggest any change in annual rainfall as time passes? Check for an association between rainfall and year.
