Unoccupied Seats on Flights Cause Airlines to Lose Revenue

Unoccupied seats on flights cause airlines to lose revenue. Suppose a large airline wants to estimate its average number of unoccupied seats per flight over the past year. Two hundred and twenty-five flight records are randomly selected, and the number of unoccupied seats is noted, with a sample mean of 11.6 seats and a standard deviation of 4.1 seats. Calculate a 90 percent confidence interval for μ, the mean number of unoccupied seats per flight during the past year.

A) [4.86, 18.34]
B) [11.25, 11.95]
C) [11.57, 11.63]
D) [11.15, 12.05]
E) [11.30, 12.20]