Exam 7: Sampling and Sampling Distributions

A random sample of size 36 is taken from a population with mean and standard deviation . Refer to Exhibit 7-5.The probability that the sample mean is between 15 and 18 is _______.

A population consists of all items of interest in a statistical problem.

A large accounting firm gives out 1,000 job offers every year to new college graduates.Suppose that 85% of those that received offers accept the position.The following shows the number of graduates that have accepted jobs in the last four years. Number of job offers accepted: a.Construct the centerline and the upper and lower control limits for the chart. B)Does the company need to worry about its ability to attract college graduates to the firm?

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

A random sample of nine cast aluminum pots is taken from a production line once every hour.The interior diameter of the pots is measured and the sample mean is calculated.The target for the diameter is 12' and the standard deviation for the pot diameter is 0.05'.Assume the pot diameter is normally distributed. A)Construct the centerline and the upper and lower control limits for the

If a population is known to be normally distributed,what can be said of the sampling distribution of the sample mean drawn from this population?

A random sample of size 36 is taken from a population with mean and standard deviation . Refer to Exhibit 7-5.The probability that the sample mean is greater than 18 is _______.

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. Refer to Exhibit 7-10.What is the probability that at least 50 respondents of a random sample of 100 Mississippi residents do NOT identify themselves as conservative?

Suppose that,on average,electricians earn approximately dollars per year in the United States.Assume that the distribution for electrician's yearly earnings is normally distributed and that the standard deviation is dollars. Refer to Exhibit 7-2.Given a sample of four electricians,what is the standard deviation for the sampling distribution of the sample mean?

A local company makes snack size bags of potato chips.Each day,the company produces batches of 400 snack size bags using a process designed to fill each bag with an average of 2 ounces of potato chips.However,due to imperfect technology,the actual amount placed in a given bag varies.Assume the amount placed in each of the 400 bags is normally distributed and has a standard deviation of 0.1 ounces.What is the probability that a sample of 40 bags has an average weight of at least 2.02 ounces?

A random sample of size 100 is taken from a population described by the proportion . Refer to Exhibit 7-6.What is the expected value and the standard deviation for the sampling distribution of the sample proportion?

The Office of Career Services at a major university knows that 74% of its graduates find full-time positions in the field of their choosing within six months of graduation.Suppose the Office of Career Services surveys 25 alumni six months after graduation. A)What is the probability that at least 80% of the alumni have a job in the field of their choosing? B)What is the probability that between 60% and 76% of the alumni have a job in the field of their choosing? C)What is the probability that fewer than 60% of the alumni have a job in the field of their choosing?

The labor force participation rate is the number of people in the labor force divided by the number of people in the country that are of working age and not institutionalized.The BLS reported in February of 2012 that the labor force participation rate in the United States was 63.7% (Calculatedrisk.com).A marketing company asks 120 working-age people if they either have a job or are looking for a job,or,in other words,whether they are in the labor force. Refer to Exhibit 7-8.What is the probability that between 60% and 62.5% of those surveyed are members of the labor force?

Which of the following is considered an estimator?

If we had access to data that encompass the entire population,then the values of the parameters would be known and no statistical inference would be needed.

In early 2012,the United States Congress approval rating was approximately 10% (Reuters.com).In a poll of 400 Americans,what is the probability that their approval rating is between 8% and 12%?

A random sample of 49 cast aluminum pots is taken from a production line once every day.The number of defective pots is counted.The proportion of defective pots has been closely examined in the past and is believed to be 0.05. Refer to Exhibit 7-11.What are the upper and lower control limits for the chart?

How does the variance of the sample mean compare to the variance of the population?

A school is required by the government to give some randomly chosen students a standardized test.From previous experience,the school knows about 68% of their students will receive passing scores in math and English.To improve funding,the school needs to score at least 70% on the standardized test.This year the school can decide if it wants to test 100 or 200 students.Should the school test 100 or 200 students? Explain.

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. Refer to Exhibit 7-9.What is the probability that from a sample of 40 Indianapolis residents,fewer than 95% were rooting for the Giants in Super Bowl XLIV?