Please help me, my book is wrong and I lost my class notes!

Unoccupied seats on flights cause airlines to lose revenue. Suppose a large airline wants to estimate its mean number of unoccupied seats per flight over the past year. To accomplish this, the records of 225 flights are randomly selected and the number of unoccupied seats is noted for each of the sampled flights. The sample mean is 11.6 seats and the sample standard deviation is 4.2 seats. Construct a 95% confidence interval.
Alpha
Standard deviation
Sample size
Mean
Confidence Interval
z or t-score
Error
Lower
Upper