You want to test the effects of water aerobics on resting heart rate. you decide to test two different levels of exercise (water aerobics for 30 minutes twice a week and water aerobics for 60 minutes once per week.) you randomly find a group of 60 (30 men and 30 women) subjects for this study. what is an appropriate design for this study?

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?