Two brands of coffee were compared. Two independent random samples of 50 people each were asked to taste either Brand A or Brand B coffee, and indicate whether they liked it or not. Eighty four percent of the people who tasted Brand A liked it; the analogous sample proportion for Brand B was ninety percent.
(A) At α = 0.01, is there a significant difference in the proportions of individuals who like the two coffees? Use the p-value approach.
(B) What is the critical value(s) for the test in Part(A)?
So I understand my teacher's solution for part A but I don't really understand how they got the values for B. Can someone explain? I tried looking up tables but I couldn't find where 2.575 came from. I feel like I might be looking at the wrong table or reading them wrong.