A study was conducted to compare the mean numbers of police emergency calls per 8-hour shift in two districts of a large city. Samples of 100 8-hour shifts were randomly selected from the police records for each of the two regions, and the number of emergency calls was recorded for each shift. The sample statistics are listed here: Sample size region 1: 100
Sample size region 2: 100
Sample mean region 1: 2.4
Sample mean region 2: 3.1
Sample variance region 1: 1.44
Sample variance region 2: 2.64
Find a 90% confidence interval for the difference in the mean numbers of police emergency calls per shift between the two districts of the city. Interpret the interval.