Answer Happy

4. A poorly written research paper states a confidence interval for the mean reaction time to an experiment as 83.6+11.515 seconds, but forgot to mention what the confidence level was. However, the paper did say that the population standard deviation is o - 35, and the sample size was n -25. a. What was the confidence level used for the confidence interval stated in the paper?

b. Using the same sample results, how could you lower the margin of error to below 10 seconds?