A psychologist studying the dynamics of marriage wanted to know how many hours per week the average American couple spends discussing marital problems. The sample mean of 155 randomly selected couples turned out to be 2.6 hours, with s = 1.8.
a. Find the 95 percent confidence interval for the mean of the population.
b. A European study had already estimated the population mean to be 3 hours per week for European couples. Are the American couples significantly different from the European couples at the .05 level? How does your answer to part A make it easy to answer Part B?