A one-sided confidence interval is one that has either an upper confidence limit or a lower confidence limit, but not both. For instance, an upper-tail interval would be developed when we wish to place an upper limit on the population parameter and have no concem about the lower limit. An upper-tail confidence limit will be:+Za (s/n); A lower-tail limit will be: - Za (s/n). An ambulance service wants to place an upper limit on its average response time, with 95% confidence. A sample of 50 recent calls is chosen to estimate the mean amount of time from when the call is received until the ambulance reaches the scene of an emergency. The sample shows = 8.4 minutes and s = 3.4 minutes. Calculate the upper-tail confidence limit.