Exam 12: Inference About a Population

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:

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.

The t-distribution is used in a confidence interval for a mean when the actual standard error is not known.

Researchers determine that 60 Puffs tissues is the average number of tissues used during a cold.Suppose a random sample of 100 Puffs users yielded the following data on the number of tissues used during a cold: = 52 and s = 22.Using the sample information provided,the value of the test statistic is:

A professor of statistics refutes the claim that the proportion of Republican voters in Michigan is at most 44%.To test the claim,the hypotheses: H₀: p = 0.44,H₁: p ≠ 0.44,should be used.

Which of the following conditions is needed regarding the chi-squared test statistic for the test of variance?

A random sample is drawn from a normal distribution with mean μ and variance σ².The random variable (n − 1)S² / σ² has a chi-squared probability distribution with n degrees of freedom.

Under what condition(s)does the test statistic for p have an approximate normal distribution?

The chi-squared test and estimator of the population variance ____________________(are/are not)valid if the population is slightly to moderately nonnormal.

In estimating the total of a population of size N,where N is very large compared to the sample size,the confidence interval estimator of the total is .

Employees in a large company are entitled to 15-minute water breaks.A random sample of the duration of water breaks for 10 employees was taken with the times shown as: 12,16,14,18,21,17,19,15,18,and 16.Assuming that the times are normally distributed,is there enough evidence at the 5% significance level to indicate that on average employees are taking longer water breaks than they are entitled to?

When the population standard deviation is unknown and the population is normal,the test statistic for testing hypotheses about μ is the ____________________-distribution with ____________________ degrees of freedom.

Physicians A random sample of 200 physicians shows that there are 36 of them who make at least $400,000 a year. ​ ​ -{Physicians Narrative} Can we conclude at the 1% significance level that the true proportion of physicians in the population who make at least $400,000 a year is less than 0.24?

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: 1: Concerned about eating healthy foods 2: Concerned about weight 3: Concerned about health because of illness 4: Unconcerned 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.

Sinus Drug A company claims that 10% of the users of a certain sinus drug experience drowsiness.In clinical studies of this sinus drug,81 of the 900 subjects experienced drowsiness ​ ​ -{Sinus Drug Narrative} Is there enough evidence at the 5% significance level to infer that the competitor is correct?

As a manufacturer of guitars,a major corporation wants to estimate the proportion of guitar players who are right-handed.How many golfers must be surveyed if they want to be within 0.02,with a 95% confidence? a.Assume that there is no prior information that could be used as an estimate of . b.Assume that the manufacturer has an estimate of found from a previous study,which suggests that 75% of guitar players are right-handed.

The test statistic used to test hypotheses about the population variance has a(n)____________________ distribution with ____________________ degrees of freedom.

In estimating the population mean with the population standard deviation unknown,if the sample size is 16,there are 8 degrees of freedom.

Single Mothers' Ages A random sample of 10 single mothers was drawn from a Obstetrics Clinic.Their ages are 22,17,27,20,23,19,24,18,19,and 24 years. ​ ​ -{Single Mothers' Ages Narrative} What is the required condition of the techniques used in the previous questions? What graphical device can you use to check to see if that required condition is satisfied?

Which of the following statements is correct regarding mass marketing?