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Ch. 6 - Confidence Intervals
Larson - Elementary Statistics: Picturing the World 8th Edition
Larson8th EditionElementary Statistics: Picturing the WorldISBN: 9780137493470당신이 사용하는 게 아니라요?교과서 변경
6장, 문제 6.Q.5

You research the salaries of senior-level civil engineers and find that the population mean is \$131,935. In Exercise 4, does the t-value fall between -t0.95 and t0.95?

검증된 단계별 안내
1
Identify the null hypothesis (H0) and the alternative hypothesis (H1). The null hypothesis typically states that there is no significant difference, while the alternative hypothesis suggests there is a difference.
Determine the sample mean, sample size, and sample standard deviation from Exercise 4 (these values are necessary to calculate the t-value).
Calculate the t-value using the formula: t = (x-μ)sn, where x is the sample mean, μ is the population mean, s is the sample standard deviation, and n is the sample size.
Find the critical t-values for a 95% confidence level (t0.95 and -t0.95) using a t-distribution table or statistical software. The degrees of freedom (df) are calculated as df = n - 1.
Compare the calculated t-value to the critical t-values. If the t-value falls between -t0.95 and t0.95, the null hypothesis is not rejected; otherwise, it is rejected.

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이 영상 해법은 위 문제에 도움이 된다고 튜터들이 추천한 것입니다.
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3m

주요 개념

질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.

Population Mean

The population mean is the average of a set of values in a complete population. In this context, it represents the average salary of all senior-level civil engineers, which is $131,935. Understanding the population mean is crucial for making inferences about the data and comparing it to sample statistics.
추천 영상:
가이드 코스
04:48
Population Standard Deviation Known

t-Distribution

The t-distribution is a type of probability distribution that is symmetric and bell-shaped, similar to the normal distribution but with heavier tails. It is used in statistics when the sample size is small or the population standard deviation is unknown. The t-values, such as -t0.95 and t0.95, represent critical values that help determine the range of values for hypothesis testing.
추천 영상:
가이드 코스
05:50
Critical Values: t-Distribution

Hypothesis Testing

Hypothesis testing is a statistical method used to make decisions about a population based on sample data. It involves formulating a null hypothesis and an alternative hypothesis, then using test statistics (like t-values) to determine whether to reject the null hypothesis. In this case, checking if the t-value falls between -t0.95 and t0.95 helps assess the significance of the sample mean in relation to the population mean.
추천 영상:
가이드 코스
06:21
Step 1: Write Hypotheses
관련 실천
교과서 질문

The data set represents the amounts of time (in minutes) spent checking email for a random sample of employees at a company.

c. Repeat part (b), assuming σ = 3.5 minutes. Compare the results.

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교과서 질문

[APPLET] The winning times (in hours) for a sample of 20 randomly selected Boston Marathon Women’s Open Division champions from 1980 to 2019 are shown in the table at the left. Assume the population standard deviation is 0.068 hour. (Source: Boston Athletic Association)

a. Find the point estimate of the population mean.

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교과서 질문

[APPLET] The winning times (in hours) for a sample of 20 randomly selected Boston Marathon Women’s Open Division champions from 1980 to 2019 are shown in the table at the left. Assume the population standard deviation is 0.068 hour. (Source: Boston Athletic Association)

b. Find the margin of error for a 95% confidence level.

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교과서 질문

In Exercises 27–30, find the critical values and for the level of confidence c and sample size n.

c = 0.90, n = 16

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교과서 질문

In a random sample of 12 senior-level civil engineers, the mean annual earnings were \$133,326 and the standard deviation was \$36,729. Assume the annual earnings are normally distributed and construct a 95% confidence interval for the population mean annual earnings for senior-level civil engineers. Interpret the results. (Adapted from Salary.com)

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교과서 질문

[APPLET] The winning times (in hours) for a sample of 20 randomly selected Boston Marathon Women’s Open Division champions from 1980 to 2019 are shown in the table at the left. Assume the population standard deviation is 0.068 hour. (Source: Boston Athletic Association)

d. Does it seem likely that the population mean could be greater than 2.52 hours? Explain.

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