All freshmen at success university take an orientation class. the professors plan on taking an SRS of 70 of the 800 freshman and asking them twice whether they agree with the statement, “If i struggle with my homework, I can find help,” once before the class and once after. they plan to look at the difference (after-before) between the proportions of freshmen who agree with the statement. suppose that before the class, 30% of the freshmen agree, while after the class, 85% agree. why is it not appropriate for the professors to use this formula for the standard deviation of the distribution of the difference in sample proportions?

Quick! a survey of 57 customers was taken at a bookstore regarding the types of books purchased. the survey found that 33 customers purchased mysteries, 25 purchased science fiction, 18 purchased romance novels, 12 purchased mysteries and science fiction, 9 purchased mysteries and romance novels, 6 purchased science fiction and romance novels, and 2 purchased all three types of books. a) how many of the customers surveyed purchased only mysteries? b) how many purchased mysteries and science fiction, but not romance novels? c) how many purchased mysteries or science fiction? d) how many purchased mysteries or science fiction, but not romance novels? e) how many purchased exactly two types of books?