Acomputer system administrator notices that computers running a particular operating system seem to freeze up more often as the installation of the operating system ages. she measures the time (in minutes) before freeze-up for seven computers one month after installation, and for nine computers seven months after installation. the results are as follows: one month after install 207.4 233.1 215.9 235.1 225.6 244.4 2453 seven months after install: 84.3 53.2 127.3 201.3 174.2 246.2 149.4 156.4 104.3 let ? x represent the population mean for the first month and lety represent the population mean for the seventh month. find a 95% confidence interval for the difference ? x-? r. round down the degrees of freedom to the nearest integer and round the answers to three decimal places. the 95% confidence interval is