Exam 7: Sampling Distributions

SCENARIO 7-4 According to a survey, only 15% of customers who visited the web site of a major retail store made a purchase.Random samples of size 50 are selected. -Referring to Scenario 7-4, the standard deviation of all the sample proportions of customers who will make a purchase after visiting the web site is _.

SCENARIO 7-5 According to an article, 19% of the entire population in a developing country has high-speed access to the Internet.Random samples of size 200 are selected from the country's population. -Referring to Scenario 7-5, among all the random samples of size 200, 90 % will have more than% who have high-speed access to the Internet.

SCENARIO 7-2 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 Scenario 7-2, what is the probability that the sample mean selling price was more than $110,000?

The amount of time required for an oil and filter change on an automobile is normally distributed with a mean of 45 minutes and a standard deviation of 10 minutes.A random sample of 16 cars is selected.95% of all sample means will fall between what two values?

For sample sizes greater than 30, the sampling distribution of the mean will be approximately normally distributed

A study at a college in the west coast reveals that, historically, 45% of the students are minority students.The expected percentage of minority students in their next group of freshmen is.

For sample size 16, the sampling distribution of the mean will be approximately normally distributed

SCENARIO 7-6 Online customer service is a key element to successful online retailing.According to a marketing survey, 37.5% of online customers take advantage of the online customer service.Random samples of 200 customers are selected. -Referring to Scenario 7-6, 95% of the samples that proportion symmetrically around the population proportion will have between % and % of the customers who take advantage of online customer service.

SCENARIO 7-4 According to a survey, only 15% of customers who visited the web site of a major retail store made a purchase.Random samples of size 50 are selected. -Referring to Scenario 7-4, the mean of all the sample proportions of customers who will make a purchase after visiting the web site is .

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.If a sample of64 fish yields a mean of 3.4 pounds, what is probability of obtaining a sample mean this large or larger?

A manufacturer of power tools claims that the mean amount of time required to assemble their top-of-the-line table saw is 80 minutes with a standard deviation of 40 minutes.Suppose arandom sample of 64 purchasers of this table saw is taken.The standard deviation of the samplingdistribution of the sample mean is minutes.

Major league baseball salaries averaged $3.26 million with a standard deviation of $1.2 million in a certain year in the past.Suppose a sample of 100 major league players was taken.Find the approximate probability that the mean salary of the 100 players exceeded $3.5 million.

The Central Limit Theorem is considered powerful in statistics because it works for any population distribution provided the sample size is sufficiently large and the population mean, and standard deviation are known.

SCENARIO 7-6 Online customer service is a key element to successful online retailing.According to a marketing survey, 37.5% of online customers take advantage of the online customer service.Random samples of 200 customers are selected. -Referring to Scenario 7-6, 90% of the samples proportions symmetrically around the population proportion will have between _% and _% of the customers who take advantage ofonline customer service.

A study at a college in the west coast reveals that, historically, 45% of the students are minority students.If random samples of size 75 are selected, the standard error of the proportion of students in the samples who are minority students is .

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 more than half of the students in the sample will be minority students.

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.

The amount of time required for an oil and filter change on an automobile is normally distributed with a mean of 45 minutes and a standard deviation of 10 minutes.A random sample of 16 cars is selected.What is the probability that the sample mean will be between 39 and 48 minutes?

The sample mean is an unbiased estimator for the population mean.

A manufacturer of power tools claims that the mean amount of time required to assemble their top-of-the-line table saw is 80 minutes with a standard deviation of 40 minutes.Suppose a random sample of 64 purchasers of this table saw is taken.The mean of the sampling distribution of the sample mean is minutes.