Problem 11Stated here are some claims or research hypotheses that are to be substantiated by sample data. In each case, identify the null hypothesis H0and the alternative hypothesis H1in terms ofthe population mean μ(a) The mean time a health insurance company takes to pay claims is less than 5 working days.(b) The average person watching a movie in a theater spends more than $7.50 on refreshments.(c) The mean time between purchases of a brand of mouthwash by loyal customers is different from 12 days.Problem 12An educator wishes to test: H0:p=0.25against H1:p>0.25where p= proportion of college football players who graduate in four years.(a) State the test statistic and the rejection region for a large sample test having α=0.05(b) If 16 out of a random sample of 50 players graduated in four years, what does the test conclude? State whether the null hypothesis is retained or rejected and make an interpretive statement about the conclusion. . . Page 6 of 14 Stat-401 Practice Exam
Name ____________________________________________ Problem 13Measurements of the amount of suspended solids in river water on 15 Monday mornings yield a mean of 44.5 mg and standard deviation of 6.5 mg. Obtain a 95% confidence interval for the mean amount of suspended solids.Problem 14Refer to the study in Problem 13 above. The water is acceptable if the mean amount of suspended solids is less than 48 mg. Construct an α=0.05test to establish that the water quality is acceptable. State the null hypothesis and alternate hypothesis. Show the formulas and calculation and state your conclusion. Page 7 of 14 Stat-401 Practice Exam
Name ____________________________________________ Problem 15Recorded here is the frequency distribution of the blood types of 120 persons who have volunteered to donate blood at a plasma center.BloodtypeOABABTotalFrequency60302010120Test the goodness of fit of the model which assumes that the four blood types occur in the proportion 4:3:2:1 in the population of plasma donors. Use α=0.05. Show the expected values, the Chi-square statistic from the data, the degrees of freedom, the Chi-square statistic from the table, and state your conclusion.Problem 16Applicants for public assistance are allowed an appeals process when they feel unfairly treated. At such a hearing, the applicant may choose self-representation or representation by an attorney. The appeal may result in an increase, decrease, or no change in the aid recommendation. Court records of 340 appeals cases provided the following data:Amount of AidIncreasedUnchangedDecreasedSelf6010020Attorney807010Test the hypothesis that the appeals decision and the type of representation are independent. Test
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- Spring '08
- Normal Distribution, graduate student