he Illinois State Toll Highway Authority is conducting a study to estimate the mean one-way distance to work for tollway commuters. The project manager desires a 5-mile bound on the error of estimation at 90% confidence. The population standard deviation is unknown, and a "best guess" of 21.75 miles is used as the planning value for ?. Use the Distributions tool to help you answer the questions that follow. Select a Distribution Distributions 0 23 The z-value for a 90% confidence interval of the population mean is In order to satisfy the requirement of a 5-mile bound on the error of estimation, a sample size no smaller th