Originally Posted by

**nac123** A manufacturer of bolts wants to determine the length of the manufactured bolts. A random sample of 160 bolts shows that the sample mean length is 2.9 inches and that the sample standard deviation is 0.1 inches.

Part (a) (5 points)

Calculate a 95 percent confidence interval for the mean length of all the bolts (i.e., for the population mean).

Part (b) (2 points)

Consider the following statement: “It is always better to construct a 99-percent confidence interval instead of a 95-percent confidence interval.” Do you agree or disagree with this statement? *Justify your answer*