We want to forecast whether the mean number of absent days per year has increased for our large workforce. A year ago the mean was known to be 12.1. A recent sample of 100 employees reveals a sample mean of 13.5 with a sample standard deviation of 1.7 days. Test at the .05 significance level to determine if the population mean has increased or if the difference between 13.5 and 12.1 simply represents sampling error.