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. How many flights should we select if we wish to estimate μ to within 2 seats and be 95 percent confident?

A) 130
B) 65
C) 33
D) 17
E) 12