1.) Use the table of cumulative areas under the normal curve to find the z-score that corresponds to the given cumulative area. If the area is not in the table, use the entry closest to the area. If the area is halfway between the two entries, use the z-score halfway between the corresponding z-scores. If convenient, use technology to find the z-score.
2). Find the margin of error for the given values of c, s, and n.
c=0.90 s=3.8 n=81
3.) Find the indicated probability using the standard normal distribution.
4.) You are given the sample mean and the sample standard deviation. Use this information to construct 90% and 95% confidence intervals for the population mean. Which interval is wider? A random sample of 39 eight ounce servings of different juice drinks has a mean of 88.5 calories and a standard deviation of 40.4 calories.
The 90% confidence interval is (___,___)
The 95% confidence interval is (___,___)
5.) Find the critical value tc for the confidence level c=0.98 and the sample size is n=6.
6.) The population mean annual salary for environment compliance specialists is about $62,000. A random sample of 38 specialists is drawn from this population. What is the probability that the mean salary of the sample is less than $59500? Assume standard deviation is $5,500.