Use the stem and leaf plot to answer questions about fuel economy.

Fuel efficiency (miles per gallon)

1 | 89

2 | 11278899

3 | 137889

4 | 3446

Key: 1 | 8 means a fuel efficiency of 18 miles per gallon.

a. Find a 90% confidence interval for the mean fuel economy. Write in the form (x,y) where x and y are rounded to 2 decimal places.

b. Which of the following statements is the correct interpretation of the confidence interval? (Select one below)

90% confidence means that 90% of the time that we take a random sample of 20 cars that the true population mean will be contained in the interval.

90% confidence means that 90% of sample means, with sample size n=20, will be in this interval.

90% confidence means that 90% is the best estimate of the proportion of cars in the whole population that have a fuel economy in this interval.

90% confidence means that 90% of cars in your sample have a fuel economy in this interval.

90% confidence means that 90% of the time that we take a random sample of 20 cars that our sample mean will be contained in the interval.