1. A sample of 750 working adults found the time spent commuting to work had a mean time of 5.4 hours per week with a standard deviation of 1.5 hours.
a) Construct a 90% confidence interval around the mean.
b) Construct a 95% confidence interval around the mean.
c) Construct a 99% confidence interval around the mean.

2. A survey of 1000 drivers was taken, out which 845 drivers reported to always wear seat belts while in a vehicle.
a) Construct a 90% confidence interval around the proportion.
b) Construct a 95% confidence interval around the proportion.
c) Construct a 99% confidence interval around the proportion.

3. A sample of 200 grocery store workers had a mean salary of $17430 per year, with a standard deviation of $2000.
a) Construct a 90% confidence interval around the mean.
b) Construct a 95% confidence interval around the mean.
c) Construct a 99% confidence interval around the mean.

4. Suppose the sample mean is 45 with a standard deviation of 13.
a) Construct a 90% confidence interval around the mean, if the sample size is 23.
b) Construct a 95% confidence interval around the mean, if the sample size is 13.
c) Construct a 99% confidence interval around the mean, if the sample size is 18.

5. It is believed that the standard deviation of the time it takes to check out at a certain retail store is 3 minutes. How large would the sample size need to be if you wanted to construct:
a) Construct a 90% confidence interval around the mean, with an error of less than 1 minute.
b) Construct a 95% confidence interval around the mean, with an error of less than 30 seconds.
c) Construct a 99% confidence interval around the mean, with an error of less than 45 seconds.

6. If you suspect that s=6, how large of a sample is necessary to have an
a) error of less than 08 at a 99% confidence
b) error of less than .03 at a 95% confidence
c) error of less than 75 at a 90% confidence

1. A sample of 750 working adults found the time spent commuting to...