3. The mean of sleep time for 50 IPTSstudents are 7 hours with standard deviation of 1 hour. The mean of sleep time for 60 IPTAstudents is 6 hours with standard deviation of 0.7 hour. Assume that the sleep time for the IPTS and IPTA students are normally distributed, find the 99% confidence interval for the difference population mean of sleep time between the IPTSand IPTA students. Interpret the answer resulted. a) Assume the population variance are same b) Assume the population variance are different