1. A torque wrench used in the final assembly of cylinder heads has a process standard deviation of 5.0 lb-ft. The engineers have specified that a process average of 135 lb-ft is desirable. For a simple random sample of 30 nuts that the machine has recently tightened, the sam- ple mean is 137.0 lb-ft. Construct and interpret the 95% confidence interval for the current process mean. Discuss the possibility that the machine may be in need of adjustment to correct the process mean.
2. There are approximately 113 million television households in the United States. A ratings service would like to know, within 5 percentage points and with 95% confidence, the percentage of these households who tune in to the first episode of a network miniseries. How many television households must be included in the sample?
Source: The World Almanac and Book of Facts 2009, p. 291.