Consider the data below of inches of rainfall per month for a region in the Northwestern United States:

Plains

April 20.1

May 15.3

June 19.8

July 17.4

August 16.8

Using SPSS, assume that the standard deviation of the population is 2.041 inches and find a 98% confidence interval for the average rainfall per month in this region. How many monthsâ€™ worth of data would we need to look at to be sure that our margin of error is less than . 5?

**Subject Mathematics General Statistics**