1 a. A random sample of 37 adults living in Hamilton determined their mean work commute time to be 53 minutes.The population standard deviation is 14 minutes.Assume a Normal Distribution applies.Calculate a 99% confidence interval for the mean work commute time of a Hamilton adult.

32.05 minutes to 41.95 minutes

49.21 minutes to 56.79 minutes

47.07 minutes to 58.93 minutes

b. The best point estimate for the population mean is the sample mean,\bar{x}

x

True

False

c An environmental agency is concerned that a large percentage of cars are violating clean air emissions standards.The agency would like to check a sample of vehicles in order to estimate that percentage with a margin of error of 4% and 95% confidence.An initial study of 100 cars revealed 14% of cars had faulty emission systems.How manyadditionalvehicles should be sampled for a full investigation?

d Based on a random sample of 124 college students, 68% had a part-time job.

Calculate a 99% confidence interval for the proportion of college students who have a part-time job.

56% to 80%

61% to 75%

57% to 79%