Exam 7: Sampling and Sampling Distributions

A fast-food restaurant uses an average of 110 grams of meat per burger patty.Suppose the amount of meat in a burger patty is normally distributed with a standard deviation of 20 grams.What is the probability that the average amount of meat in four randomly selected burgers is less than 105 grams?

Suppose that,on average,electricians earn approximately µ = $54,000 per year in the United States.Assume that the distribution for electricians' yearly earnings is normally distributed and that the standard deviation is σ = $12,000 dollars.What is the probability that the average salary of four randomly selected electricians is more than $50,000 but less than $60,000?

In a small town,there are 3,000 registered voters.An editor of a local newspaper would like to predict the outcome of the next election;in particular,he is interested in the likelihood that Eli Brady will be elected.The editor believes that Eli,a local hero,will garner 54% of the vote.A poll of 500 registered voters is taken.Assuming that the editor's belief is true,calculate: a.The expected value and the standard deviation (standard error)of the sample proportion.b.The probability that the sample proportion score is more than 0.58.

The standard deviation of (standard error of the sample mean)equals the population standard deviation divided by the square root of the sample size,or, equivalently.

Nonresponse bias occurs when those responding to a survey or poll differ systematically from the nonrespondents.

Under what condition is the finite population correction factor used for computing the standard error of and ?

Selection bias occurs when _______.

Professor Elderman has given the same multiple-choice final exam in his Principles of Microeconomics class for many years.After examining his records from the past 10 years,he finds that the scores have a mean of 76 and a standard deviation of 12.What is the probability that a class of 36 students will have an average greater than 70 on Professor Elderman's final exam?

Selection bias occurs when the sample is mistakenly divided into strata,and random samples are drawn from each stratum.

When a statistic is used to estimate a parameter,the statistic is referred to as an estimator.A particular value of the estimator is called an estimate.

Which of the following meets the requirements of a simple random sample?

In any production process,variation in the quality of the end product is inevitable.Chance variation,or common variation,refers to _______.

According to the 2011 Gallup daily tracking polls (www.gallup.com,February 3,2012),Mississippi is the most conservative U.S.state,with 53.4 percent of its residents identifying themselves as conservative.What is the probability that at least 100 but fewer than 115 respondents of a random sample of 200 Mississippi residents identify as conservative?

In stratified random sampling,the population is first divided up into mutually exclusive and collectively exhaustive groups,called strata.A stratified sample includes randomly selected observations from each stratum,which are proportional to the stratum's size.

According to the 2011 Gallup daily tracking polls (www.gallup.com,February 3,2012),Mississippi is the most conservative U.S.state,with 53.4 percent of its residents identifying themselves as conservative.What is the probability that fewer than 45 respondents of a random sample of 100 Mississippi residents do not identify themselves as conservative?

The finite population correction factor for the standard error of the mean should be used when the ratio of the sample size to the size of population exceeds _______.

Super Bowl XLVI was played between the New York Giants and the New England Patriots in Indianapolis.Due to a decade-long rivalry between the Patriots and the city's own team,the Colts,most Indianapolis residents were rooting heartily for the Giants.Suppose that 90% of Indianapolis residents wanted the Giants to beat the Patriots.What is the probability that,of a sample of 100 Indianapolis residents,at least 15% were rooting for the Patriots in Super Bowl XLVI?

Which of the following is not a form of bias?

According to the central limit theorem,the distribution of the sample means is normal if _______.

A preferred approach to quality control is the _________ approach.