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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: 9780137493470Not the one you use?Change textbook
All textbooksLarson 8th EditionCh. 7 - Hypothesis Testing with One SampleProblem 7.2.26
Chapter 7, Problem 7.2.26

Finding Critical Values and Rejection Regions In Exercises 23–28, find the critical value(s) and rejection region(s) for the type of z-test with level of significance α. Include a graph with your answer.


Right-tailed test, α = 0.08

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Step 1: Understand the problem. This is a right-tailed z-test with a significance level (α) of 0.08. A right-tailed test means the rejection region is in the right tail of the standard normal distribution.
Step 2: Recall the relationship between the significance level (α) and the critical value. The critical value is the z-score that corresponds to the cumulative probability of 1 - α in the standard normal distribution.
Step 3: Use a z-table or statistical software to find the z-score that corresponds to a cumulative probability of 1 - α = 1 - 0.08 = 0.92. This z-score is the critical value for the test.
Step 4: Define the rejection region. For a right-tailed test, the rejection region consists of all z-scores greater than the critical value. This means if the test statistic falls in this region, you reject the null hypothesis.
Step 5: Visualize the rejection region on a standard normal distribution graph. Mark the critical value on the horizontal axis, shade the area to the right of this value to represent the rejection region, and label the area as α = 0.08.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Critical Value

A critical value is a point on the scale of the test statistic beyond which we reject the null hypothesis. In hypothesis testing, it is determined based on the significance level (α) and the type of test (one-tailed or two-tailed). For a right-tailed test, the critical value corresponds to the z-score that marks the threshold for the upper tail of the distribution.
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Rejection Region

The rejection region is the range of values for the test statistic that leads to the rejection of the null hypothesis. In a right-tailed test, this region is located to the right of the critical value. It represents the area under the curve where the probability of observing a test statistic is less than the significance level (α), indicating that the observed result is statistically significant.
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Step 4: State Conclusion

Level of Significance (α)

The level of significance, denoted as α, is the probability of rejecting the null hypothesis when it is actually true (Type I error). It is a threshold set by the researcher before conducting the test, commonly used values are 0.05, 0.01, and in this case, 0.08. The choice of α influences the critical value and the size of the rejection region, impacting the test's sensitivity.
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Related Practice
Textbook Question

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.


Left-tailed test, α=0.10, n=38

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Textbook Question

True or False? In Exercises 5–10, determine whether the statement is true or false. If it is false, rewrite it as a true statement.


In a hypothesis test, you assume the alternative hypothesis is true.

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Textbook Question

Explain how to test a population proportion p.

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Textbook Question

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.


Two-tailed test, α=0.05, n=27

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Textbook Question

Hypothesis Testing Using Rejection Region(s) In Exercises 39–44, (a) identify the claim and state H0 and Ha, (b) find the critical value(s) and identify the rejection region(s), (c) find the standardized test statistic z, (d) decide whether to reject or fail to reject the null hypothesis, and (e) interpret the decision in the context of the original claim.


Light Bulbs A light bulb manufacturer guarantees that the mean life of a certain type of light bulb is at least 750 hours. A random sample of 25 light bulbs has a mean life of 745 hours. Assume the population is normally distributed and the population standard deviation is 60 hours. At alpha= 0.02, do you have enough evidence to reject the manufacturer’s claim?

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Textbook Question

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.


Video Game Systems A researcher claims that the percentage of U.S. gamers that are women is not 50%.

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