Exam 13: Hypothesis Testing: Describing a Single Population

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A Type II error is defined as: A. rejecting a true null hypothesis. B. rejecting a fal se null hypothesis. C. not rejecting a true null hypothesis. D. not rejecting a false null hypothesis.

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D

A Type I error is represented by α\alpha , and is the probability of rejecting a true null hypothesis.

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During the Gulf War, a government official claimed that the average car owner refilled the fuel tank when there was more than 3 litres of petrol left. To check the claim, 10 cars were surveyed as they entered a service station. The amount of petrol (in litres) was measured and recorded as shown below. 3 5 3 2 3 3 2 6 4 1 Assume that the amount of petrol remaining in the tanks is normally distributed with a standard deviation of 1 litre. Can we conclude at the 10% significance level that the official was correct?

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H0:μ=3H _ { 0 } : \mu = 3 . H1:μ>3H _ { 1 } : \mu > 3 .
Test statistic: z = 0.63.
Rejection region: z > z.10z _ { .10 } = 1.28.
Conclusion: Don't reject H0 { H } _ { 0 } . Conclude that the official was incorrect.

If a sample size is increased at a given α\alpha level, the probability of committing a Type I error increases.

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The power of a test is the probability that a true null hypothesis will be rejected.

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If the value of the sample mean xˉ\bar { x } is close enough to the hypothesised value of the population mean μ\mu , then: A the hypothesised value is definitely true. B the hypothesised value is definitely false. C we reject the null hypothesis. D we don't reject the null hypothesis.

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Suppose you intend to test the claim that a typical high school student in Sydney spends more than $50 a week on mobile phone calls. Which hypotheses are used to test the claim? A. :\mu50 :\mu<50 B. :\mu=50 :\mu50 C. :\mu50 :\mu=50 D. :\mu=50 :\mu>50

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In testing the hypotheses H0:μ=24.4H _ { 0 } : \mu = 24.4 . H1:μ>24.4H _ { 1 } : \mu > 24.4 . the following information was given: σ=7.6,n=60,xˉ=25.52,α=0.06\sigma = 7.6 , \quad n = 60 , \quad \bar { x } = 25.52 , \quad \alpha = 0.06 . a. Calculate the value of the test statistic. b. Set up the rejection region. c. Determine the p-value. d. Interpret the result.

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The probability of making a Type I error and the level of significance are the same.

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The p-value criterion for hypothesis testing is to retain the null hypothesis if: A p -value =\alpha B p -value <\alpha C p -value >\alpha D -\alpha p-value <\alpha

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If we do not reject the null hypothesis, we conclude that there is enough statistical evidence to infer that the null hypothesis is true.

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In a one-tail test, the p-value is found to be equal to 0.032. If the test had been two-tailed, the p-value would have been: A. 0.064. B. 0.080 C. 0.016. D. 0.066.

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A random sample of 100 families in a large city revealed that on the average these families have been living in their current homes for 35 months. From previous analyses, we know that the population standard deviation is 30 months. Compute the probability of a Type II error if the true mean number of months families in this city have been living in their current homes is 29.

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In testing the hypotheses H0:μ=H _ { 0 } : \mu = 75. H1:H _ { 1 } : μ\mu < 75. if the value of the Z test statistic equals 1.78, then the p-value is: A. 0.0.375 B. 0.4625 C. 0.9625 D. 0.5375

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The p-value of a test is the probability of observing a test statistic at least as extreme as the one computed, given that the null hypothesis is true.

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The power of a test is denoted by: A. \alpha. B. \beta C. 1-\alpha D. 1-\beta

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When testing a value of the population mean, if the population variance is unknown, then we must do a t-test

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The probability of a Type I error is denoted by: A. \beta. B. 1-\beta C. \alpha. D. 1-\alpha.

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We cannot commit a Type I error when the: A null hypothesis is true. B level of significance is 0.10 . C null hypothesis is false. D test is a two-tail test.

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If we reject a null hypothesis at the 0.05 level of significance, then we must also reject it at the 0.10 level.

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