Assignment:
Find the 97% confidence interval, given a sample mean of 128.37, sample standard deviation of 37.3, and sample size of 50. What is the width of the confidence interval? Suppose that you want to cut the confidence interval by 50% (i.e., the new width should be half the previous one). How many additional observations would you use?
Provide complete and step by step solution for the question and show calculations and use formulas.