I have a question I've been working on and I've noticed that my solution differs from the textbook solution. I would have considered it a mistake, but the next 4 questions are similar with the same solution "mistake"? Aside from not converting the % to 0.885, I am wondering about part b. It says to cut the confidence interval to one third; in the solution they cut it to 2, why is that? (oddly enough, in the next question, they ask to cut the confidence interval to 1/2 but use 1/3 in the solution) is there something I am not understanding?