In a Manufacturing Process, a Random Sample of 9 Manufactured

Multiple Choice

In a manufacturing process, a random sample of 9 manufactured bolts has a mean length of 3 inches with a variance of .09 and is normally distributed. What is the 90 percent confidence interval for the true mean length of the manufactured bolt?

A) 2.8355 to 3.1645
B) 2.5065 to 3.4935
C) 2.4420 to 3.5580
D) 2.8140 to 3.1860
E) 2.9442 to 3.0558