An issue of Science News (Vol. 163, No. 22, pp XXXXXXXXXXreported that the Women’s Health initiative cast doubts on the benefit of hormone -replacement therapy. Researchers randomly divided 4532...

An issue of Science News (Vol. 163, No. 22, pp. 341-342) reported that the Women’s Health initiative cast doubts on the benefit of hormone -replacement therapy. Researchers randomly divided 4532 healthy women over the age of 65 years into two groups. One group, consisting of 2229 women, received hormone-replacement therapy, the other group, consisting of 2303 women received placebo. Over 5 years, 40 of the women receiving the hormone -replacement therapy were diagnosed with dementia, compared with 21 of those getting placebo.

b. Determine and interpret a 90% confidence interval for the difference in dementia risk rates for healthy women over 65 years old who take hormone -replacement therapy and those who do not.