Exam 12: Inference About a Population

When a population is small, we must adjust the test statistic and interval estimator using the ____________________ population correction factor.

The t-statistic has two variables: the sample ____________________ and the sample ____________________.

A major electronics store chain is interested in estimating the average amount its credit card customers spent on their first visit to the chain's new store in the mall.Fifteen credit card accounts were randomly sampled and analyzed with the following results: = $50.50 and s² = 400.A 95% confidence interval for the average amount the credit card customers spent on their first visit to the chain's new store in the mall is:

To estimate ____________________ when the population size N is small, the confidence interval estimator is .

In order to determine the p-value associated with hypothesis testing about the population mean $\mu$ , it is necessary to know the value of the test statistic.

If we have some idea about the value of sample proportion , we use that value in determining the sample size needed to estimate the population proportion p.

An investor is concerned with the risk associated with a portfolio of stocks.He draws a random sample of nine monthly returns (expressed as a percentage of the initial investment).These data follow: 2, 5, -6, 10, 1, 2, -3, 0, and 7.Find a 95% confidence interval estimate of the population variance.

A random sample of size 15 taken from a normally distributed population revealed a sample mean of 75 and a sample variance of 25.The upper limit of a 95% confidence interval for the population mean would equal:

If we are testing for an improvement in the consistency of an operation or the manufacturing of a product, the alternative hypothesis would have a(n) ____________________ sign in it.

Target marketing focuses on satisfying the demands of all segments of the entire market.

Tractor Dealership An accountant was performing an audit for a tractor dealership.An auditor wants to examine the monetary error made by the purchasing order department in the month of July.He decided to randomly sample 100 of the 925 purchase orders for the month of July, and found the amount of error in each one.The statistics for this sample were: = $6.0 and s = $17.012. -{Tractor Dealership Narrative} Why should the finite population correction factor (FPCF) be used for this problem? Explain.

Healthy Foods In segmenting the frozen meal market in Spain, a food manufacturer uses health and diet consciousness as the segmentation variable.Four segments are developed and coded as follows: To distinguish between groups, surveys are conducted.On the basis of a questionnaire, people are categorized as belonging to one of these groups.A recent survey asked a random sample of 1,500 Spanish adults (20 and over) to complete the survey.Out of the 1,500 people surveyed, 360 indicated that they are concerned about eating healthy foods.The most recent information available reveals that there are 40,256,000 Spanish adults who are 20 and over. -{Healthy Foods Narrative} Estimate with 95% confidence the proportion p of Spanish adults who classify themselves as concerned about eating healthy.

The sampling distribution of is approximately normal if the sample size is more than 30.

Pilots' Union Contract A union composed of several thousand pilots is preparing to vote on a new contract.A random sample of 500 pilots yielded 320 who planned to vote yes.It is believed that the new contract will receive more than 60% yes votes. -{Pilots' Union Contract Narrative} Can we infer at the 5% significance level that the new contract will receive more than 60% yes votes?

To produce a confidence interval estimator for the total, we multiply the lower and upper confidence limits of the interval estimator of p by ____________________.

Mass marketing refers to the mass production and marketing by a company of all products the company produces for a single segment of the entire market.

A random sample of 25 observations is selected from a normally distributed population.The sample variance is 10.In the 95% confidence interval for the population variance, the upper limit is:

Mystic Pizza Mystic Pizza in Mystic, Connecticut, advertises that they deliver your pizza within 15 minutes of placing an order or it is free.A sample of 25 customers is selected at random.The average delivery time in the sample was 13 minutes with a sample standard deviation of 4 minutes. -{Mystic Pizza Narrative} We want to know whether Mystic can make this claim or not.Test to determine if we can infer at the 5% significance level that the population mean delivery time is less than 15 minutes.

Tire Rotation The manager of a service station is in the process of analyzing the number of times car owners rotate the tires on their cars.She believes that the average motorist rotates his or her car's tires less frequently than recommended by the owner's manual (two times per year).In a preliminary survey she asked 14 car owners how many times they rotated their cars' tires in the last 12 months.The results are 1, 1, 2, 0, 3, 3, 0, 1, 0, 1, 2, 3, 3, and 1. -{Tire Rotation Narrative} Does this data provide sufficient evidence at the 10% significance level to indicate that the manager is correct?

In market segmentation, if education is the segmentation variable of interest, then possible segments of the market include: some high school, high school graduates, some college, college or university graduates.