Exam 7: Sampling and Sampling Distributions

A sample of size 25 provides a sample variance of 400.The standard error,in this case equal to 4,is best described as the estimate of the standard deviation of means calculated from samples of size 25.

TABLE 7-5 According to a survey,only 15% of customers who visited the website of a major retail store made a purchase.Random samples of size 50 are selected. -Referring to Table 7-5,what proportion of the samples will have less than 15% of customers who will make a purchase after visiting the website?

TABLE 7-5 According to a survey,only 15% of customers who visited the website of a major retail store made a purchase.Random samples of size 50 are selected. -A study at a college in the west coast reveals that,historically,45% of the students are minority students.If a random sample of size 75 is selected,the probability is ________ that between 30% and 50% of the students in the sample will be minority students.

The owner of a fish market has an assistant who has determined that the weights of catfish are normally distributed,with mean of 3.2 pounds and standard deviation of 0.8 pound.What percentage of samples of 4 fish will have sample means between 3.0 and 4.0 pounds?

The sample mean is an unbiased estimate of the population mean.

Assume that house prices in a neighborhood are normally distributed with a standard deviation of $20,000.A random sample of 16 observations is taken.What is the probability that the sample mean differs from the population mean by more than $5,000?

When dealing with human surveys,we are usually interested in sampling with replacement.

The Central Limit Theorem is important in statistics because

If the amount of gasoline purchased per car at a large service station has a population mean of 15 gallons and a population standard deviation of 4 gallons,then 99.73% of all cars will purchase between 3 and 27 gallons.

Coverage error results in a ________.

To find out the potential impact of a new zoning law on a neighborhood,the legislators conduct a focus group interview by inviting the members of the housing owners association of that neighborhood.This is an example of a

Items or individuals in a judgment sample are chosen according to their probability of occurrence.

________ results from the exclusion of certain groups of subjects from a population frame.

If the population distribution is symmetric,the sampling distribution of the mean can be approximated by the normal distribution if the samples contain 15 observations.

Which of the following yields a simple random sample?

At US Data Corporation's website,they advertised that "Because of our commitment to quality and our vast amount of industry knowledge and experience,we have grown to be one of America's leading providers of mailing lists,marketing data,sales leads and research data.We maintain databases of information on consumers and businesses nationwide that set industry standards for mission critical currency,reliability and accuracy." Trying to reach 500 potential donors for their annual phone donation campaign,a local fire department purchased a list of donors from the company.This list is an example of a

The only way one can eliminate sampling error is to take the whole population as the sample.

TABLE 7-3 The mean selling price of new homes in a small town over a year was $115,000.The population standard deviation was $25,000.A random sample of 100 new home sales from this city was taken. -Referring to Table 7-3,without doing the calculations,state in which of the following ranges the sample mean selling price is most likely to lie?

TABLE 7-1 The manager of the customer service division of a major consumer electronics company is interested in determining whether the customers who have purchased a DVD player made by the company over the past 12 months are satisfied with their products. -Referring to Table 7-1,the manager decides to ask a sample of customers,who have bought a DVD player made by the company and filed a complaint over the past year,to fill in a survey about whether they are satisfied with the product.This method will most likely suffer from

The amount of time it takes to complete an examination has a left skewed distribution with a mean of 65 minutes and a standard deviation of 8 minutes.If 64 students were randomly sampled,the probability that the sample mean of the sampled students exceeds 71 minutes is approximately 0.