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Unformatted text preview: STAT 2610 Exam 2 review Spring 2010 1. If the null hypothesis is false it is impossible to commit a Type I error. True or false? a. True b. False Use the following information to answer the next two questions The level of calcium in the blood of healthy young adults follows a normal distribution with mean μ =10 milligrams per deciliter and standard deviation 8 . = σ . A clinic measures the blood calcium of 100 healthy adults and the mean of these 100 measurements is 8 . 9 = x . To make an inference if the mean calcium level in the population from which these adults came from is less than 10 milligrams, you test the hypotheses: H : 10 = μ H 1 : 10 < μ 2. If the test statistic is -2.5, what is the p-value of this test? a. 0.9938 b. 0.0062* c. 0.0047 d. 0.9953 e. 0.5 3. In your hypotheses test that the mean calcium level in blood is less than 10 milligrams, your test would be significant at 10 . = α level of significance. You may also conclude that a. The test is significant at 05 . = α level of significance b. The test is significant at 01 . = α level of significance c. The test is significant at 02 . = α level of significance d. All of the above* e. None of the above 4. In a test of statistical hypotheses, the p-value tells us a. If the null hypothesis is true b. If the alternative hypothesis is true c. The largest level of significance at which the null hypotheses can be rejected d. The smallest level of significance at which the null hypothesis can be rejected* e. None of the above 5. The weekly earnings of students in one age group are normally distributed with a standard deviation of $81. A researcher wishes to estimate the mean weekly earnings of students in this age group. Find the sample size needed to ensure, with 98% confidence, that the sample mean will not differ from the population mean by more than $5. a. 1425* b. 700 c. 88 d. 10 e. 18 1 Use the following to answer the next two questions. The average waiting time per customer at a fast food restaurant has been 7.5 minutes. The customer waiting time has a normal distribution. The manager claims that the use of a new cashier system will decrease the average customer waiting time in the store. 6. Based on a random sample of 16 customer transactions the mean waiting time is 6.3 minutes and the standard deviation is 2 minutes per customer. What is the value of the test statistic for testing the manager’s claim? a. -2.4* b. 9.6 c. 2.4 d. -1.2 e. -0.6 7. A random sample of 12 customer transactions has been recorded and the sample mean and standard deviation determined. At a significance level of .05, what is the decision rule condition? We would reject the null hypothesis if: a. t*< -1.796 * b. t* < -1.782 c. Z* > 1.645 d. t* > 1.796 e. Z* < -1.645 Use the following information to answer the next three questions The heights (in inches) of males in the U.S. are believed to be normally distributed with mean μ . The average height of a random sample of 25 American adult males is found to be...
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This note was uploaded on 09/18/2011 for the course STAT 2610 taught by Professor Syvantek during the Spring '08 term at Auburn University.
- Spring '08