Finding Critical Values and Confidence Intervals. In Exercises 5-8, use the given information to find the number of degrees of freedom, the critical values x? and x*, and the confidence interval estimate of o. The samples are from Appendix B and it is reasonable to assume that a simple random sample has been selected from a population with a normal distribution.

1. Nicotine in Menthol Cigarettes 95% confidence; n = 25, s = 0.24 mg.
2. Weights of Dollar Coins 95% confidence; n = 20, s = 0.04111 g.