Use the given information to find the number of degrees of freedom, the critical values y and x , 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 98% confidence; n = 28, s = 0.23 mg. Click the icon to view the table of Chi-Square critical values. . . . df = (Type a whole number.) x =(Round to three decimal places as needed.) XR =(Round to three decimal places as needed.) The confidence interval estimate of o is |mg