Exam 7: Sampling and Sampling Distributions

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 is between 45 and 52 minutes?

TABLE 7-7 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 Table 7-7,95% of the samples proportions symmetrically around the population proportion will have between ________ % and ________ % of the customers who take advantage of online customer service.

Major league baseball salaries averaged $3.26 million with a standard deviation of $1.2 million in a recent year.Suppose a sample of 100 major league players was taken.Find the approximate probability that the mean salary of the 100 players was no more than $3.0 million.

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 of 16 fish is taken,what would the standard error of the mean weight equal?

Suppose a sample of n = 50 items is selected from a population of manufactured products and the weight,X,of each item is recorded.Prior experience has shown that the weight has a probability distribution with μ = 6 ounces and σ = 2.5 ounces.Which of the following is true about the sampling distribution of the sample mean if a sample of size 15 is selected?

A company selling apparel online sends out emails every Monday to all its customers who made a purchase.This is an example of a

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,if a customer survey questionnaire is included in all the DVD players made and sold by the company over the past 12 months,this method of collecting data will most like suffer from

Major league baseball salaries averaged $3.26 million with a standard deviation of $1.2 million in a recent year.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 standard error of the mean for a sample of 100 is 30.In order to cut the standard error of the mean to 15,we would

The question "Is your household income last year somewhere between $50,000 and $100,000?" will most likely result in coverage error.

Measurement error will become an ethical issue when the findings are presented without reference to sample size and margin of error.

If the population distribution is skewed,in most cases the sampling distribution of the mean can be approximated by the normal distribution if the samples contain at least 30 observations.

TABLE 7-6 According to an article,19% of the entire population in a developing country have high-speed access to the Internet.Random samples of size 200 are selected from the country's population. -Referring to Table 7-6,among all the random samples of size 200,________ % will have more than 30% who have high-speed access to the Internet.

If you randomly select a student from the first row of a business statistics class and then every other fifth student thereafter until you get a sample of 20 students,this is an example of a convenience sample.

The amount of bleach a machine pours into bottles has a mean of 36 oz.with a standard deviation of 0.15 oz.Suppose we take a random sample of 36 bottles filled by this machine.The probability that the mean of the sample exceeds 36.01 oz.is ________.

You stand at the main entrance to a departmental store and pick the first 20 customers that enter the store after it has opened its door for business on a single day.This is an example of a systematic sample.

Which of the following sampling methods will more likely be susceptible to ethical violation when used to form conclusions about the entire population?

Which of the following yields a stratified sample?

A sample of 300 subscribers to a particular magazine is selected from a population frame of 9,000 subscribers.If,upon examining the data,it is determined that no subscriber had been selected in the sample more than once,

When participants are allowed to self-select into the sample,you have a nonprobability sample.