In Chapter 20, we learned that to compute an approximate 90% confidence interval, the appropriate multiplier is 1.645 instead of 2.0. This works for confidence intervals for one mean or the difference in two means as well. Consult Table 21.2 on page 458 to find the means and standard errors for the ages of males in couples that remained intact and that separated in the study of Australian couples.
a. Compute an approximate 90% confidence interval for the difference in mean ages for the populations of men in couples that remained intact and that separated.
b. Based on your result in part (a) could you conclude with 90% confidence that the difference in mean ages observed in the samples represents a real difference in mean ages in the population? Explain.