For question 19. Only

the a = 0.05 IC 18. TVaholics According to the American Time Use Survey, the typical American spends 154.8 minutes (2.58 hours) per day watching television. A survey of 50 Internet users results in a mean time watching television per day of 128.7 minutes, with a standard deviation of 46.5 minutes. Conduct the appropriate test to determine if Internet users spend less time watching television at the a = 0.05 level of significance. Source: Norman H. Nie and D. Sunshine Hillygus. "Where Does Internet Time Come From? A Reconnaissance." IT & Society, 1(2). 19. Age of Death-Row Inmates In 2002, the mean age of an inmate on death row was 40.7 years, according to data from the U.S. Department of Justice. A sociologist wondered whether the mean age of a death-row inmate has changed since then. She randomly selects 32 death-row inmates and finds that their mean age is 38.9, with a standard deviation of 9.6. Construct a 95% confidence interval about the mean age. What does the interval imply? 20. Energy Consumption In 2001, the mean household expenditure for energy was $1493, according to data from the U.S. Energy Information Administration. An economist wanted to know whether this amount has changed significantly from its 2001 level. In a random sample of 35 households, he found the mean expenditure (in 2001 dollars) for energy during the most recent year to be $1618, with a standard deviation $321. Construct a 95% confidence interval about the mean energy expenditure. What does the interval imply? NW 21. Waiting in Line The mean waiting time at the drive-through of a fast-food restaurant from the time an order is placed to the time the order is received is 84.3 seconds. A manager devises a new drive- through system that he believes will decrease wait time. He initiates the new system at his restaurant and measures the wait time for 10 randomly selected orders. The wait times are provided in the table. 75.9 65.1