How Many Birds Do Domestic Cats Kill? Exercise 6.23 discusses the headline "Domestic cats kill many more wild birds in the United States than scientists thought," and estimates the proportion of domestic cats that hunt outside. A separate study used KittyCams to record all activity of n = 55 domestic cats that hunt outdoors. The video footage showed that the mean number of kills per week for these cats was 2.4 with a standard deviation of 1.51. Find and interpret a 99% confidence interval for the mean number of kills per week by US household cats that hunt outdoors. Note that here t = 2.670