A hotel chain wanted to learn about the level of experience of its general managers. A random sample of 14 general managers was taken, and these managers had a mean of 11.72 years of experience. Suppose that the standard deviation of years of experience for all general managers in the chain is known to be 3.2 years.

What is the lower limit of a 95% confidence interval for the mean experience of all general managers in this hotel chain?

(a) 10.04 years

(b) 13.40 years

(c) 5.45 years

(d) 9.89 years