1.An infinite population has a standard deviation of 10. A random sample of 100 items from this population is selected. The sample mean is determined to be 60. At 90% confidence, what is the margin of error?

2.The z value for a 99% confidence interval estimation is

3.The t value for a 80% confidence interval estimation with 24degrees of freedom (not the sample size n) is

4.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 3.6. The 80% confidence interval for the population mean is

5.A random sample of 81 observations has a mean of 20, a median of 21, a mode of 22, and a standard deviation of 3.6. The 80% confidence interval for the population mean is