Exam 9: Sampling Distributions and Confidence Intervals for Proportions

A small business ships specialty homemade candies to anywhere in the world. Past records indicate that the weight of orders is normally distributed. Suppose a random sample of 16 orders is selected and each is weighed. The sample mean was found to be 110 grams with a standard deviation of 14 grams. A. Describe the sampling distribution for the sample mean. b. What is the standard error? c. For 90% confidence, what is the margin of error? d. Based on the sample results, create the 90% confidence interval and interpret.

The unemployment rate of persons with a disability is typically higher than for those with no disability. Recent statistics report that the national rate of unemployment among This group is 14.5%. The local government of a small city wants to determine the rate in Its region to within ±5%, with 90% confidence. How many individuals with disabilities Should they sample?

In economic downturns, companies attempt to downsize their workforces by offering early retirement incentives to older employees. A survey of 723 companies found that 195 engage in such downsizing practices. The 99% confidence interval for the Proportion of companies that downsize their workforces by offering early retirement Incentives is

A publishing company conducted a survey of its readership and found that 60% subscribed to Food & Wine, 30% subscribed to Wine Spectator, and 25% subscribed to Both. The probability that a reader does not subscribe to either is

A researcher is conducting a study on Internet use. He decides to first categorize the population by education level (high school, college graduate, advanced degree, etc.) and Then survey a select number from each category. This sampling strategy is called

IT staff for a large corporation has developed the following probability distribution for the number of calls requiring troubleshooting problems per day. Based on the Distribution, the expected number of calls per day is