1. If n=23, x(x-bar)=42, and s=6, construct a confidence interval at a 80% confidence level. Assume the data came from a normally distributed population. one decimal place. ___< <___
2. Assume that a sample is used to estimate a population proportion . Find the margin of error M.E. that corresponds to a sample of size 457 with a mean of 24.1 and a standard deviation of 21.6 at a confidence level of 99.8%. Report ME accurately to one decimal place because the sample statistics are presented with this accuracy. The answer should be obtained without any preliminary rounding. However, the critical value may be rounded to 3 decimal places. M.E=
3. Assume that a sample is used to estimate a population mean . Find the 95% confidence interval for a sample of size 770 with a mean of 68.9 and a standard deviation of 10.1. Enter your answer as a tri-linear inequality accurate to one decimal place (because the sample statistics are reported accurate to one decimal place). __ < < __. The answer should be obtained without any preliminary rounding. However, the critical value may be rounded to 3 decimal places.
4. You intend to estimate a population mean with a confidence interval. You believe the population to have a normal distribution. Your sample size is 9. Find the critical value that corresponds to a confidence level of 90%. (Report answer accurate to three decimal places with appropriate rounding.) t_a/2 =