Stats exam 4

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A critical​ value, zα​, denotes the​ _______.

.z-score with an area of α to its right.

Which of the following is NOT an observation about critical​ values?

A critical value is the area in the​ right-tail region of the standard normal curve.

Which of the following groups has terms that can be used interchangeably with the​ others?

Percentage, Probability, and Proportion

When analyzing​ polls, which of the following is NOT a​ consideration?

The sample should be a voluntary response or convenience sample.

What does it mean to say that the confidence interval methods for the mean are robust against departures from​ normality?

The confidence interval methods for the mean are robust against departures from​ normality, meaning they work well with distributions that​ aren't normal, provided that departures from normality are not too extreme.

A newspaper provided a​ "snapshot" illustrating poll results from 1910 professionals who interview job applicants. The illustration showed that​ 26% of them said the biggest interview turnoff is that the applicant did not make an effort to learn about the job or the company. The margin of error was given as ±3 percentage points. What important feature of the poll was​ omitted?

The confidence level

Which of the following is NOT a requirement for constructing a confidence interval for estimating a population mean with σ ​known?

The confidence level is​ 95%.

Which of the following is NOT a property of the Student t​ distribution?

The standard deviation of the Student t distribution is s=1.

A magazine provided results from a poll of 1500 adults who were asked to identify their favorite pie. Among the 1500 ​respondents, 14​% chose chocolate​ pie, and the margin of error was given as ±3 percentage points. Describe what is meant by the statement that​ "the margin of error was given as ±3 percentage​ points."

The statement indicates that the interval 14​%±3​% is likely to contain the true population percentage of people that prefer chocolate pie.

Which of the following is NOT a requirement for constructing a confidence interval for estimating the population​ proportion?

The trials are done without replacement.

Which concept below is NOT a main idea of estimating a population​ proportion?

Using a sample statistic to estimate the population proportion is utilizing descriptive statistics.

Which of the following would be a correct interpretation of a​ 99% confidence interval such as 4.1<μ<​5.6?

We are​ 99% confident that the interval from 4.1 to 5.6 actually does contain the true value of μ.

Which of the following would be a correct interpretation of a​ 99% confidence interval such as 4.1<μ<​5.6?

We are​ 99% confident that the interval from 4.1 to 5.6 actually does contain the true value of μ.

Refer to the accompanying data display that results from a sample of airport data speeds in Mbps. The results in the screen display are based on a​ 95% confidence level. Write a statement that correctly interprets the confidence interval. TInterval ​(13.046,22.15) x=17.598 Sx=16.01712719 n=50

We have​ 95% confidence that the limits of 13.05 Mbps and 22.15 Mbps contain the true value of the mean of the population of all data speeds at the airports.

A food safety guideline is that the mercury in fish should be below 1 part per million​ (ppm). Listed below are the amounts of mercury​ (ppm) found in tuna sushi sampled at different stores in a major city. Construct a 98​% confidence interval estimate of the mean amount of mercury in the population. Does it appear that there is too much mercury in tuna​ sushi?

Yes, because it is possible that the mean is greater than 1 ppm.​ Also, at least one of the sample values exceeds 1​ ppm, so at least some of the fish have too much mercury.

The number of​ _______ for a collection of sample data is the number of sample values that can vary after certain restrictions have been imposed on all data values.

degrees of freedom

A​ _______ is a single value used to approximate a population parameter.

point estimate

The​ _______ is the best point estimate of the population mean.

sample mean


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