1. The average lateness for one of the top airline companies is 10 minutes. The Standard Deviation of the lateness measure is calculated as 3. An airplane arrived 8.5 minutes after the stated arrival time. Calculate the Z-score of the airplanes lateness
2. Health insurers and the federal govt are both putting pressure on the hospitals to shorten average length of stay of their patients. A random sample of 20 hospitals in one state had a mean length of stay for non heart patients in 2000 of 3.8 days and a SD of 1.2 days. Calculate a 95% confidence interval for the population mean LOS for non heart patients in the states hospitals.
3. At a local manufacturing plant employees must complete new machine set ups within 30 minutes. New machine set up times can be described by a normal model with a mean of 22 minutes and a SD of four minutes. What percent of new machine set ups take more than 30 minutes?
4.A random sample of 100 European professional soccer players has an average age of 27 years and a SD of 4 years. We would like to decide if there is enough evidence to establish that average age of European soccer players is significantly more than 26 years. What is the nul hypothesi?
5. What is the sample value of the test statistic?
6. At 0.01 level of significance, what decision would you make? Include proper reason.