Quiz%20IV-%20Solutions_1

Quiz%20IV-%20Solutions_1 - QUIZ IV- BIT 2405- Solutions A...

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QUIZ IV- BIT 2405- Solutions A random sample of 16 students selected from the student body of a large university had an average age of 25 years. We want to determine if the average age of all the students at the university is significantly different from 24. Assume the distribution of the population of ages is normal with a standard deviation of 2 years. 1. The correct set of hypotheses is 1. H 0 : p 24 H a : p 24 2. H 0 : 25 H a : 25 3. H 0 : 24 H a : 24 4. None of the above 2. The test statistic is 1. 1.96 2. 2.00 3. 1.645 4. 0.05 null the reject to Fail t t t t t 2 / 2 / 2 / ; 131 . 2 ; 2 4 2 24 25 3. At a .05 level of significance, it can be concluded that the mean age is 1. not significantly different from 24 2. significantly different from 24 3. significantly less than 24 4. significantly less than 25 A random sample of 100 people was taken. Eighty of the people in the sample favored Candidate A. We are interested in determining whether or not the proportion of the population in favor of Candidate A is significantly more than 75%. 4. The p -value is 1. 0.2112 2. 0.05 3. 0.025 4. None of the above H 0 : p .75 H a : p > .75  15 . 1 100 25 . 72 . 75 . 8 . 0 z ; 1251 . ) ( 0 z Z P value p reject to fail 05 . 1251 . 5. At a .05 level of significance, it can be concluded that the proportion of the population in favor of candidate A is 1. significantly greater than 75% 2. not significantly greater than 75% 3. significantly greater than 80% 4. not significantly greater than 80%
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Problems 6-8 In order to determine the average price of hotel rooms in Atlanta, a sample of 64 hotels was selected. It was determined that the average price of the rooms in the sample was $112. The population standard deviation is known to be $16. Use a 0.05 level of significance and determine whether or not the average room price is significantly different from $108.50. 6. The correct set of hypotheses is 1. H 0 : 108.50 H a : 108.50 2. H 0 : 108.50 H a : > 108.50 3. H 0 : 108.50 H a : 108.50 4. H 0 : 112 H a : 112 7. The test statistic is 1. 1.75 2. -1.75 3. 1.645 4. 0.05 2 / ; 75 . 1 64 16 50 . 108 112 z z 1.96; -1.96 < 1.75 < 1.96 8. At a .05 level of significance, 1. do not reject H 0 , there is not sufficient evidence at α .05 to conclude that the average room price is significantly different from $108.50 2. Reject H 0 , there is not sufficient evidence at α .05 to conclude that the average room price is significantly different from $108.50 3. Reject H 0 , there is sufficient evidence at α .05 to conclude that the average room price is significantly different from $108.50 4. None of the above 9. A carpet company advertises that it will deliver your carpet within 15 days of purchase. A sample of 49 past customers is taken. The average delivery time in the sample was 16.2 days. Assume the population standard deviation is known to be 5.6 days. Give the p-value and the decision 1. 0.0668; there is not sufficient evidence at α .05 to conclude that the average delivery time is more than what is advertised 2. 0.0668; there is sufficient evidence at α .05 to conclude that the average delivery time is more than what is advertised 3. 0.0495; there is sufficient evidence at α .05 to conclude that the average
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This note was uploaded on 10/26/2009 for the course BIT 2405 taught by Professor Plkitchin during the Spring '08 term at Virginia Tech.

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Quiz%20IV-%20Solutions_1 - QUIZ IV- BIT 2405- Solutions A...

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