Twenty-five volunteers who had developed cold symptoms within the last 24 hours were given zinc lozenges to take every 2 to 3 hours until their cold symptoms were gone. The mean overall duration of symptoms was 4.5 days with a standard deviation of 1.6 days.
The selected cases have a distribution which appears to be symmetric and bell-shaped.
a. Construct a 99% confidence interval for the mean overall duration of symptoms in a population of individuals who used zinc lozenges.
b. In a previous test, the mean overall duration of symptoms for volunteers who were told to drink an herbal tea for relief of their symptoms was 7 days. Based on your confidence interval, do you think that using the lozenges reduces the overall duration of symptoms compared to using the herbal tea?
The solution provides step by step method for the calculation of confidence interval for population mean. Formula for the calculation and Interpretations of the results are also included. Interactive excel sheet is included. The user can edit the inputs and obtain the complete results for a new set of data.