Use the given information to find the number of degrees of​ freedom, the critical values χ2L and χ2R​, and the confidence interval estimate of σ. It is reasonable to assume that a simple random sample has been selected from a population with a normal distribution. Nicotine in menthol cigarettes 99​% ​confidence; n=23​, s=0.28 mg. df = (Type a whole​ number.)
χ2L = ​(Round to three decimal places as​ needed.)
χ2R = ​(Round to three decimal places as​ needed.)
The confidence interval estimate of σ is __ mg < σ < __ mg. ​(Round to two decimal places as​ needed.)