1. I wish to find a 95% confidence interval for the mean number of times men change channels with a remote control during a commercial. Based on a preliminary study, I estimate σ = 15. How many commercials' worth of data do I need to have a margin of error no more than 3?
A. 10
B. 97
C. 96
2. I have computed a 95% confidence interval for the mean, μ, of a population as (13, 20). Based on this interval,
A. there is a 95% chance μ is in the interval.
B. 95% of the observations lie in the interval.
C. the method gives correct results 95% of the time.
3. A researcher wants to know if tougher sentencing laws have had the desired impact in terms of deterring crime. He plans to select a sample of states which have enacted a "3 strikes" law and compare violent crime rates before the law was enacted and two years later. The correct set of hypotheses to test are
