360 CHAPTER 7 Hypothesis Testing with One Sample Using and Interpreting Concepts Stating the Null and Alternative Hypotheses In Exercises 25–30, write the claim as a mathematical statement. State the null and alternative hypotheses, and identify which represents the claim. 25. Tablets A tablet manufacturer claims that the mean life of the battery for a certain model of tablet is more than 8 hours. 26. Shipping Errors As stated by a company’s shipping department, the number of shipping errors per million shipments has a standard deviation that is less than 3. 27. Base Price of an ATV The standard deviation of the base price of an all-terrain vehicle is no more than $320. 28. Attendance An amusement park claims that the mean daily attendance at the park is at least 20,000 people. 29. Paying for College According to a recent survey, 54% of today’s college students used student loans to pay for college. (Source: The Federal Reserve) 30. College Debt According to a recent survey, 14% of adults currently carry student loan debt. (Source: The Federal Reserve) Identifying Type I and Type II Errors In Exercises 31–36, describe type I and type II errors for a hypothesis test of the indicated claim. 31. Repeat Customers A used textbook selling website claims that at least 60% of its new customers will return to buy their next textbook. 32. Flow Rate An urban planner claims that the noontime mean traffic flow rate on a busy downtown college campus street is 35 cars per minute. 33. Chess A local chess club claims that the length of time to play a game has a standard deviation of more than 12 minutes. 34. Video Game Systems A researcher claims that the percentage of U.S. gamers that are women is not 50%. 35. Security A campus security department publicizes that at most 25% of applicants become campus security officers. 36. Phone Repairs A cell phone repair shop advertises that the mean cost of repairing a phone screen is less than $120. Identifying the Nature of a Hypothesis Test In Exercises 37– 42, state H0 and Ha in words and in symbols. Then determine whether the hypothesis test is left-tailed, right-tailed, or two-tailed. Explain your reasoning. Sketch a normal sampling distribution and shade the area for the P-value. 37. Security Alarms A security expert claims that at least 14% of all homeowners have a home security alarm. 38. Clocks A manufacturer of grandfather clocks claims that the mean time its clocks lose is no more than 0.02 second per day. 39. Golf A golf analyst claims that the standard deviation of the 18-hole scores for a golfer is less than 2.1 strokes. 40. Lung Cancer A report claims that lung cancer accounts for 25% of all cancer diagnoses. (Source: American Cancer Society)
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