Read anything lately? Th e Denver Public Library wants to estimate the percent of Denver households with an adult who has read at least one book in the last month. Th e homes of 400 people who have library cards are sampled, and it turns out that 90% of these households have an adult who has read a book in the past month.

Is 90% likely to be a biased estimate for the true percent of Denver households with an adult who has read at least one book in the last month? Explain why or why not.