Chs. 7 & 8 Practice Problems Name: ___________________ Instructions: Please complete the following applied statistical exercises to the best of your ability after reading Chapters 7 & 8. You get full points if this exercise is fully complete. However, you will lose points if you leave questions blank. Chapter 7 1. If you are a human resources manager and you randomly selected 5 job candidates to interview out of hundreds of equallyqualified candidates that applied for a job without replacement, what would be the standard error of the mean if the standard deviation is 1? x= n 2. The U.S. Census Bureau announced that the population mean sales of houses was $322,100. Assume that the standard deviation of the prices is $90,000. If you select a sample size of 100, what's the cumulative probability that the sample mean will be less than $346,000 for all possible house samples? (Tip: First find the Z value, then find the cumulative probability to determine the percentage) Z= X n What's the cumulative probability according to the Ztable? Chapter 8.1 3. A random sample of 100 credit sales in a department store showed an average sale of $120.00. From past data, it is known that the standard deviation of the population is $40.00. a. Determine the standard error of the mean. b. With a .95 probability (e.g., 1.96), determine the margin of error. c. What is the 95% confidence interval of the population mean? 4. In an effort to estimate the mean amount spent per customer for dinner at a major Atlanta restaurant, data were collected for a sample of 49 customers. Assume a population standard deviation of $5. a. At 95% confidence (e.g., 1.96), what is the margin of error? b. If the sample mean is $24.80, what is the 95% confidence interval for the population mean? 5. If the confidence level that a statistician chooses is 99%, then... a. what is the alpha () coefficient? _______ b. what is the % of error? ______ c. what is the Za/2? ______