Exam 7: Sampling and Sampling Distributions

The campaign manager for a candidate for governor in Arizona wants to conduct a poll to better understand his candidate's chances for the upcoming election.a.What is the population of interest? b.Why may the poll be biased if a simple random sample of voters in the last gubernatorial election (four years prior)is taken?

Stratified random sampling is preferred when the objective is 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 50 respondents of a random sample of 100 Mississippi residents do not identify themselves as conservative?

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?

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.Professor Elderman offers his class of 36 a pizza party if the class average is above 80.What is the probability that he will have to deliver on his promise?

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 200 Indianapolis residents,fewer than 170 were rooting for the Giants in Super Bowl XLIV?

Acceptance sampling is _______.

In early 2012,the U.S.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 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?

We are told that 8% of college graduates,under the age of 25 are unemployed.What is the probability that at least 200 college graduates under age 25 are employed?

Which of the following is considered an estimate?

For qualitative data,the most appropriate control chart to monitor the proportion of a certain characteristic is a(n)

Cluster sampling is preferred when the objective is to _______.

Statistics are used to estimate population parameters,particularly when it is impossible or too expensive to poll an entire population.A particular value of a statistic is referred to as a(n)_______.

According to the IRS,the average refund in the 2011 tax year was $3,109.Assuming that the standard deviation for these refunds was $874,what is the standard error of the sample mean for a random sample of 50 tax returns?

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 less than 15 is _______.

If is normally distributed then we can transform it into a(n)_______ normal random variable.

Over the entire six years that students attend an Ohio elementary school,they are absent,on average,28 days due to influenza.Assume that the standard deviation over this time period is σ = 9 days.Upon graduation from elementary school,a random sample of 36 students is taken and asked how many days of school they missed due to influenza.The probability that the sample mean is between 25 and 30 school days is _______.

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 _______.

Successful firms must focus on the quality of the products and services they offer.Which factor or factors contribute to the quest for quality?