Use the given information to find the number of degrees of freedom, the critical values chi Subscript Upper L Superscript 22L and chi Subscript Upper R Superscript 22R,

and the confidence interval estimate of sigma. 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; nequals=24,

sequals=0.22 mg.