In a manufacturing process a random sample of 36 bolts manufactured has a mean length of 3 inches with a standard deviation of .3 inches. What is the 99% confidence interval for the true mean length of the bolt?
a) 2.902 to 3.098
b) 2.884 to 3.117
c) 2.865 to 3.136
d) 2.228 to 3.772
e) 2.465 to 3.205