Use the given information to find the number of degrees of freedom, the critical values x and XR, and the confidence interval estimate of o. It is reasonable to assume that a simple random sample has been selected from a population with a normal distribution. Nicotine in menthol cigarettes 90% confidence; n=29, s=0.23 mg. Click the icon to view the table of Chi-Square critical values. df = (Type a whole number.)