Exam 7: Statistical Inference: Estimating a Population Mean

The fact that the sampling distribution of the sample mean can be approximated by a normal distribution whenever the sample size is large is based on the:

Fisher-Lopez wants to determine the average age of customers who purchase products through its website.You've contacted a simple random sample of 5 customers, with the following results: Customer Age: 26, 21, 19, 18, 26 Assume the population distribution of customer ages is normal.Build a 90% confidence interval estimate of the average age of this customer population and report the upper bound for your interval.

According to the central limit theorem, as the sample size becomes larger the sampling distribution of the sample mean approaches a:

A population consists of items A, B, C, and D.A simple random sample will be selected from this population.Choose from the alternatives below the list of all the possible samples of size 3.

You want to estimate the average useful life of the lithium cell phone batteries that your company has just put on the market.You take a random sample of 25 batteries to be tested.The test reveals a sample average life of 1560 hours.The sample standard deviation is 68 hours.Assume that the population distribution is approximately normal.Construct a 95% confidence interval estimate of average useful life for the full population of lithium cell phone batteries produced by your company.Report the margin of error indicated by your interval.

An examination of all the members of a particular population is called a(n):

You plan to take a random sample from a population of 500 items and build a 95% confidence interval estimate of the population mean.You want a margin of error no bigger than plus/minus 5.You estimate the population standard deviation to be 100.How large a sample is needed?

What is the purpose of the sampling distribution of the sample mean?

You want to estimate the average GMAT score for all students who took the Logitano GMAT Preparation course during the past 2 years.You select a random sample of 100 such students from a comprehensive list of all students who took the course over the last two years and find that the average GMAT score for the sample was 1040.Assume you know the population standard deviation here is 83 points.Produce the 95% confidence interval estimate of the mean GMAT score for the population of Logitano students represented by the sample.Report the upper bound for your interval.

Which of the following describes how an interval estimate is constructed?

You want to estimate the average GMAT score for all students who took the Logitano GMAT Preparation course during the past 2 years.You select a random sample of 100 such students from a comprehensive list of all students who took the course over the last two years and find that the average GMAT score for the sample was 1040.Assume you know the population standard deviation here is 83 points.Produce the 95% confidence interval estimate of the mean GMAT score for the population of Logitano students represented by the sample.Report the margin of error shown in your interval.

The table below shows the names of the sales staff at Porter-Waggoner Accounting, together with the number of major accounts that each one services: You plan to take all possible samples of size 3 that could be selected from this population (sampling without replacement) and then calculate the mean number of accounts for each of the samples.Which of the tables below shows the sampling distribution of the sample mean that would result?

Statistical inference is:

You want to estimate the average useful life of the lithium cell phone batteries that your company has just put on the market.You take a random sample of 25 batteries to be tested.The test reveals a sample average life of 1560 hours.The sample standard deviation is 68 hours.Assume that the population distribution is approximately normal.Construct a 95% confidence interval estimate of average useful life for the full population of lithium cell phone batteries produced by your company.Report the upper bound for your interval.

From a population that is normally distributed with an unknown standard deviation, a sample of 25 elements is selected.For an interval estimation of the population mean, the proper distribution to use is the:

The sampling distribution of the sample mean:

The average annual health care cost in a random sample of 600 U.S.adults is $8562.If the standard deviation for health care costs in the population is $1230, compute the standard error of the sampling distribution of the sample mean.

The sampling distribution of the sample mean is the probability distribution of all possible values of the sample mean when samples of size n-1 are taken from a given population.

You produce a confidence interval estimate of a population mean from a simple random sample of size n.If sample size is doubled and the confidence requirement remains the same, the width of the new interval estimate will be half the width of the original.

The average annual health care cost in a random sample of 600 U.S.adults is $8562.If the standard deviation for health care costs in the population is $1230, compute the margin of error in a 90% confidence interval estimate of the mean annual health care cost for all U.S.adults.