2. (1 point) Fuel Economy, SUV The Environmental Protection Agency (EPA) publishes fuel economy values that are known to be good estimates of the fuel economy a typical driver will achieve under average driving conditions. One of the fuel economy values the EPA publishes is a combined estimate, which represents a combination of city driving (55%) and highway driving (45%). A large car rental company has 13 Ford Explorers in their fleet. They collected fuel economy data from these cars and calculated the sample mean to be 22.48 mpg and sample standard deviation as 0.75 mpg.

1. Which conditions must be met for the hypothesis test to be valid?

Check all that apply.

A. There must be an expected value of at least 5 for every vehicle in the population.

B. There must be at least 3 levels of the categorical variable.

C. There must be at least 10 successes and 10 failures among the 12 observed vehicles.

D. Population data for mpg must be nearly normal or the sample size must be at least 30.

E. The observations must be independent.

2. The car rental company is willing to assume that the conditions are met for constructing a confidence interval. Use the collected data to construct a 90% confidence interval for the mean combined fuel economy for Ford Explorers. ( ??,?? )

3. A competing car rental company decides to construct a 90% confidence interval for the mean combined fuel economy of the Chevy Equinox using the 26 cars in their fleet as a sample. They obtain an interval of (28.78,30.72). Assume that conditions have been met for constructing this interval and indicate whether each of the statements below is or is not an appropriate interpretation of this confidence interval.

appropriate not appropriate

We can be confident that 90% of Chevy Equinoxes have a combined fuel economy between (28.78, 30.72).

appropriate not appropriate

We can be 90% confident that the true mean combined fuel economy for the Chevy Equinox is between (28.78, 30.72).

appropriate not appropriate

If the company were able to obtain 100 random samples of 26 Chevy Equinoxes and used each of the samples to construct a 90% confidence interval, we would expect approximately 90 of those intervals to include the true mean combined fuel economy for this car.