It is known that the variance of a population equals 1,936. A random sample of 121 has been taken from the population. There is a 0.95 probability that the sample mean will provide a margin of error of ? A random sample of 144 observations has a mean of 20, a median of 21, and a mode of 22. The population standard deviation is known to equal 4.8. The 95.44% confidence interval for the population mean is?
A random sample of 64 students at a university showed an average age of 25 years and a sample standard deviation of 2 years. The 98% confidence interval for the true average age of all students in the university is?