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Ch. 7 - Hypothesis Testing with One Sample
Larson - Elementary Statistics: Picturing the World 8th Edition
Larson8th EditionElementary Statistics: Picturing the WorldISBN: 9780137493470당신이 사용하는 게 아니라요?교과서 변경
7장, 문제 7.5.20

In Exercises 15–22, test the claim about the population variance or standard deviation at the level of significance Assume the population is normally distributed.
Claim: σ^2>19, α=0.1. Sample statistics: s^2=28, n=17

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Step 1: Identify the null hypothesis (H₀) and the alternative hypothesis (H₁). The null hypothesis is H₀: σ² ≤ 19, and the alternative hypothesis is H₁: σ² > 19. This is a right-tailed test because the claim is that the population variance is greater than 19.
Step 2: Determine the test statistic formula for a chi-square test for variance. The formula is χ² = ((n - 1) * s²) / σ₀², where n is the sample size, s² is the sample variance, and σ₀² is the hypothesized population variance.
Step 3: Substitute the given values into the formula. Here, n = 17, s² = 28, and σ₀² = 19. Compute the test statistic χ² using these values.
Step 4: Determine the critical value for the chi-square distribution at the given significance level α = 0.1 and degrees of freedom (df = n - 1). Use a chi-square distribution table or statistical software to find the critical value for df = 16.
Step 5: Compare the calculated test statistic to the critical value. If the test statistic is greater than the critical value, reject the null hypothesis H₀. Otherwise, fail to reject H₀. Interpret the result in the context of the claim.

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주요 개념

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Population Variance and Standard Deviation

Population variance (σ²) measures the spread of a set of values in a population, while the standard deviation (σ) is the square root of the variance. These metrics are crucial for understanding the variability within a dataset. In hypothesis testing, they help determine if observed data significantly deviates from a hypothesized value.
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08:45
Calculating Standard Deviation

Hypothesis Testing

Hypothesis testing is a statistical method used to make inferences about population parameters based on sample data. It involves formulating a null hypothesis (H0) and an alternative hypothesis (H1), then using sample statistics to determine whether to reject H0. In this case, the null hypothesis would state that the population variance is less than or equal to 19.
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가이드 코스
06:21
Step 1: Write Hypotheses

Level of Significance (α)

The level of significance (α) is the probability of rejecting the null hypothesis when it is actually true, commonly set at 0.05 or 0.1. In this scenario, α=0.1 indicates a 10% risk of concluding that the population variance exceeds 19 when it does not. This threshold helps determine the critical value for making decisions in hypothesis testing.
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03:33
Finding Binomial Probabilities Using TI-84 Example 1
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교과서 질문

Finding a P-Value In Exercises 13–18, find the P-value for the hypothesis test with the standardized test statistic z. Decide whether to reject H0 for the level of significance alpha.

Left-tailed test


z=-1.68

alpha=0.05

127
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교과서 질문

Graphical Analysis In Exercises 21 and 22, state whether each standardized test statistic z allows you to reject the null hypothesis. Explain your reasoning.


a. z = -1.301

b. z = 1.203

c. z = 1.280

d. z = 1.286


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교과서 질문

Deciding on a Distribution In Exercises 31 and 32, decide whether you should use the standard normal sampling distribution or a t-sampling distribution to perform the hypothesis test. Justify your decision. Then use the distribution to test the claim. Write a short paragraph about the results of the test and what you can conclude about the claim.


Tuition and Fees An education publication claims that the mean in-state tuition and fees at public four-year institutions by state is more than \(10,500 per year. A random sample of 30 states has a mean in-state tuition and fees at public four-year institutions of \)10,931 per year. Assume the population standard deviation is \$2380. At α=0.01, test the publication’s claim.

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교과서 질문

Identifying Type I and Type II Errors In Exercises 31–36, describe type I and type II errors for a hypothesis test of the indicated claim.


Phone Repairs A cell phone repair shop advertises that the mean cost of repairing a phone screen is less than \$120.

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교과서 질문

Writing Hypotheses: Medicine A medical research team is investigating the mean cost of a 30-day supply of a heart medication. A pharmaceutical company thinks that the mean cost is less than \$60. You want to support this claim. How would you write the null and alternative hypotheses?

66
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교과서 질문

In Exercises 3–8, find the critical value(s) and rejection region(s) for the type of t-test with level of significance alpha and sample size n.

Right-tailed test, α=0.05, n=23

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