Directions: Show your work! Remember having a cell phone out today results in a zero on the exam. – A) According to an article you read online, the average teenager spends 56 hours per week using their cell phone. You think that THS students use their phones more than that so you conduct a study. You randomly sample 109 students (of the 2300 total) and find their average weekly cell phone usage to be 60 hours with a standard deviation of 22 hours. Are these findings significant at the 5% level? B) Refer to question A and answer these questions: i) Explain a Type I error in the context of the question. ii) Find the Probability of a Type I error. iii) Explain a Type II error in the context of the question. iv) Suppose one wanted to the of the test. What does this mean? “increase v) How can the power be increased? C) An assembly line produces for the transmission of a Toyota sedan. This particular assembly line produces over 2,500 gears per day. To test the machine the inspector will randomly sample 200 gears and run a diagnostic on each. If the machine is working normally, only 2% of the gears will fail the diagnostic. On a particular inspection, 8 of 200 gears fail the diagnostic. The inspector is worried that this is too high. Is this result significant at the 1% level? D) Why do some studies use an alpha value of 5% while others use an alpha value of 1% or lower? What would be the rationale for using different alpha values in different contexts? Please discuss this thoroughly using examples from class that we talked or read about. Reflect: E) your solutions. Predict your score on the exam: ____ / 40. How many hours did you study? _____
Directions: Show your work! Remember – having a cell phone out today results in a zero on the exam. A) According to an article you read online, the average teenager spends 56 hours per week using their cell phone. You think that THS students use their phones more than that so you conduct a study. You randomly sample 109 students (of the 2300 total) and find their average weekly cell phone usage to be 60 hours with a standard deviation of 22 hours. Are these findings significant at the 5% level? B) Refer to question A and answer these questions: i) Explain a Type I error in the context of the question. ii) Find the Probability of a Type I error. iii) Explain a Type II error in the context of the question. iv) Suppose one wanted to “increase the of the test. What does this mean? v) How can the power be increased? C) An assembly line produces for the transmission of a Toyota sedan. This particular assembly line produces over 2,500 gears per day. To test the machine the inspector will randomly sample 200 gears and run a diagnostic on each. If the machine is working normally, only 2% of the gears will fail the diagnostic. On a particular inspection, 8 of 200 gears fail the diagnostic. The inspector is worried that this is too high. Is this result significant at the 1% level? D) Why do some studies use an alpha value of 5% while others use an alpha value of 1% or lower? What would be the rationale for using different alpha values in different contexts? Please discuss this thoroughly using examples from class that we talked or read about. Reflect: E) your solutions. Predict your score on the exam: ____ / 40. How many hours did you study? _____
Chapter%2009%20Practice%20Test.docx