Exam 7: Sampling and Sampling Distributions

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 from a sample of 100 Indianapolis residents, fewer than 95% were rooting for the Giants in Super Bowl XLVI?

For quantitative data, the most appropriate control chart to monitor central tendency is a(n)

Social-desirability bias refers to systematic difference between a group's "socially acceptable" responses to a survey or poll and this group's ultimate choice.

A random sample of size 36 is taken from a population with mean µ = 17 and standard deviation σ = 6. What are the expected value and the standard deviation for the sampling distribution of the sample mean?

If the expected value of a sample mean equals the population mean, the sample mean is biased.

Susan has been on a bowling team for 14 years. After examining all of her scores over that period of time, she finds that they follow a normal distribution. Her average score is 225, with a standard deviation of 13. If during a typical week Susan bowls 16 games, what is the probability that her average score is more than 230?

A university administrator expects that 25% of students in a core course will receive an A. He looks at the grades assigned to 60 students. The probability that the proportion of students who receive an A is between 0.20 and 0.35 is

Susan has been on a bowling team for 14 years. After examining all of her scores over that period of time, she finds that they follow a normal distribution. Her average score is 225, with a standard deviation of 13. If during a typical month Susan bowls 64 games, what is the probability that her average score in this month is above 227?

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 60% of a random sample of 200 Mississippi residents identify themselves as conservative?

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?

A university administrator expects that 25% of students in a core course will receive an A. He looks at the grades assigned to 60 students. The probability that the proportion of students who receive an A is not between 0.20 and 0.30 is ________.

In a large metropolitan area, the top providers for television and Internet services are a phone company, a satellite company, and a cable company. The satellite company serves 43% of the homes in the area. What is the probability that in a survey of 1,000 homes, more than 447 of them are served by the satellite company?

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 inches and the standard deviation for the pot diameter is 0.05 inches. Assume the pot diameter is normally distributed. A) Construct the centerline and the upper and lower control limits for the chart. B) The means of the samples for a given eight-hour day are 12.01 12.06 11.97 12.08 11.92 11.95 11.97 12.04. Plot these values on the chart. C) Does it appear that the process is under control? Explain.

Suppose the average math SAT score for students enrolled at local community college is 490.4 with a standard deviation of 63.7. A random sample of 49 students has been selected. The standard error of the mean for this sample is ________.

According to the Bureau of Labor Statistics it takes an average of 22 weeks for someone over 55 to find a new job. Assume that the probability distribution is normal and that the standard deviation is two weeks. What is the probability that eight workers over the age of 55 take an average of more than 20 weeks to find a job?

A random sample of size 36 is taken from a population with mean µ = 17 and standard deviation σ = 6. The probability that the sample mean is greater than 18 is ________.