Question

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.)

Answer 1

Answer:

χ²R = 8.643

χ²L = 42.796

0.20 < σ < 0.45

Step-by-step explanation:

Given :

Sample size, n = 23

The degree of freedom, df = n - 1 = 23 - 1 = 22

At α - level = 99%

For χ²R ; 1 - (1 - 0.99)/2= 0.995 ; df = 22 ; χ²R = 8.643

For χ²L ; (1 - 0.99)/2 = 0.005 ; df = 22 ; χ²L = 42.796

The confidence interval of σ ;

s * √[(n-1)/χ²L] < σ < s * √[(n-1)/χ²R)]

0.28 * √(22/42.796) < σ < 0.28 * √(22/8.643)

0.2008 < σ < 0.4467

0.20 < σ < 0.45