1. Using Table F, find the value oft/2for a 99% confidence interval when the sample size is 12. 2. Using Table F, find the value oft/2 for a 90% confidence interval when the sample size is 7. 3. Using Table F, find the value oft/2for a 95% confidence interval when the sample size is 27. 4. A recent study of 28 randomly selected employees of a company showed that the mean of the distance they traveled to work was 14.3 miles. The standard deviation of this sample was 2.0 miles. Find the 95% confidence interval for (the true mean time for all employees of the company). Round your answer to one place after the decimal point. Solution: We need to find the 95% confidence interval for the mean when we do not know the population standard deviation but only the standard deviation of the sample (so this will be a t-interval, not a z-interval). The upper and lower limits of this interval are 5. A survey of 16 randomly selected websites of a certain type has a mean of 162,565 viewers for a specific week. The standard deviation of this sample is 26,854. Find the upper limit of the 95% confidence interval of the mean number of visitors per week for this type of website. Round your answer to the nearest whole number. 6. A sample of 14 randomly selected commuters in Chicago had an average commuting time of 36.4 minutes, with a standard deviation of 7.6 minutes. Find the lower limit of the 99% confidence interval of the true (population) mean. Round your answer to one place after the decimal point