Chapter 9.2, Problem 27E

Business Insider reported that a study commissioned by eBay motors found that nearly 40% of millennials who drive a car that is more than 5 years old have named their cars (“Millennials Have an Odd Habit When It Comes to Their Cars,” April 14, 2016). Suppose that this statement was based on a sample of size 800 and that 312 reported that they had named their car. Assuming that the sample was selected to be representative of the population of millennials who drive a car that is more than 5 years old, calculate and interpret a 90% confidence interval for the proportion of all millennials who drive a car that is more than 5 years old who have named their cars.