Exam 13: Hypothesis Testing: Describing a Single Population

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In a one-tail test for the population mean, if the null hypothesis is not rejected when the alternative hypothesis is true: A. a Type I error is committed. B. a Type II error is committed. C. a correct decision is made. D. a two-tail test should be used instead of a one-tail test.

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In testing the hypotheses: H0 : μ\mu = 950 H1 : μ\mu\neq\neq 950, the following information was given: ? = 1000, α\alpha = 0.05, μ\mu = 180 and n = 75. Determine μ\mu .

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In our justice system, judges instruct juries to find the defendant guilty only if there is evidence 'beyond a reasonable doubt'. In general, what would be the result if judges instructed juries: a. to compromise between Type I and Type II errors? b. never to commit a Type I error? c. never to commit a Type II error?

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When testing whether the majority of voters in an electorate will vote for a particular candidate, which of the following sets of hypotheses are correct? A :p=0.50 :p<0.50 B :p>0.50 :p=0.50 C :p=0.50 :p>0.50 D None of these choices are correct

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State which of the following set of hypotheses are appropriate. Explain a. Ho: µ = 25 H1: µ ≠ 25 b. Ho: µ > 25 H1: µ = 25 c. H0:H _ { 0 } : xˉ=35\bar { x } = 35 . H1:xˉ>35H _ { 1 } : \bar { x } > 35 . d. Ho: p = 25 H1: p ≠ 25 e. Ho: p = 0.5 H1: p > 0.5

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In a two-tail test for the population mean, if the null hypothesis is rejected when the alternative hypothesis is true, a Type I error is committed.

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In a one-tail test, the p-value is found to be equal to 0.018. If the test had been two-tailed, the p-value would have been 0.036.

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In testing the hypotheses H0:μ=60H _ { 0 } : \mu = 60 . H1:μ<60H _ { 1 } : \mu < 60 . the following information was given: σ=5,n=100,xˉ=59,α=0.05\sigma = 5 , \quad n = 100 , \quad \bar { x } = 59 , \quad \alpha = 0.05 . 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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A drug company is interested in the effectiveness of a new sleeping pill. A random sample of 50 people try the new sleeping pill and the number of additional hours of sleep (compared with the nights without any sleeping pill), X, are recorded. The sample standard deviation of X is 3 hours. a. State the null and alternative hypotheses for the claim that the new drug increases the number of hours of sleep at least by 2 hours on average. b. Using a standardised test statistic, test the hypothesis at the 5% level of significance if the sample mean of additional hours of sleep is 2.2 hours.

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In testing the hypotheses: H0 : μ\mu = 950 H1 : μ\mu \neq\neq 950, the following information was given: ? = 1000, α\alpha = 0.05, μ\mu = 180 and n = 75. It was found that β\beta = 0.2061. a. Recalculate β\beta if n = 100. b. What is the effect of increasing the sample size on the value of β\beta ?

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In testing the hypotheses H0 : μ\mu = 75. H1 : μ\mu < 75. The p-value is found to be 0.042, and the sample mean is 80. Which of the following statements is true? A. The probability of observing a sample mean at most as large as 75 from a population whose mean is 100 is 0.042 B. The smallest value of \alpha that would lead to the rejection of the null hypothesis is 0.042 . C. The probability that the population mean is smaller than 75 is 0.042 . D. None of the above statements is correct.

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In a one-tail test for the population mean, if the null hypothesis is not rejected when the alternative hypothesis is true, a Type I error is committed.

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A random sample of 100 observations from a normal population whose standard deviation is 50 produced a mean of 75. Does this statistic provide sufficient evidence at the 5% level of significance to infer that the population mean is not 80?

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In testing the hypotheses: H0:μ=25H _ { 0 } : \mu = 25 H1:μ25H _ { 1 } : \mu \neq 25 , a random sample of 36 observations drawn from a normal population, produced a mean of 22.8 and a standard deviation of 10 What is the conclusion for this hypothesis test, at 5% significance level.

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When using a t-test to test the population mean, the degrees of freedom are n - 1.

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When testing a value of the population proportion, we must do a Z-test.

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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. A) Calculate the p-value. B) Compute the probability of a Type II error if the true average amount of gas remaining in tanks is 3.5 litres.

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A Type I error occurs when we: A. reject a false null hypothesis. B. eject a true null hypothesis. C. don't reject a false null hypothesis. D. don't reject a true null hypothesis.

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In testing the hypotheses: H0:μ=H _ { 0 } : \mu = 500 H1:μH _ { 1 } : \mu \neq 500, if the value of the Z test statistic equals 2.03, then the p-value is: A. 0.0424 B. 0.4788 C. 0.9576. D. 0.0212

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A two-tail test is a test in which a null hypothesis can be rejected by an extreme result occurring in either direction.

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