In: Statistics and Probability
A chocolate chip cookie manufacturing company recorded the number of chocolate chips in a sample of 70 cookies. The mean is 22.68 and the standard deviation is 2.32.
Construct a 99% confidence interval estimate of the standard deviation of the numbers of chocolate chips in all such cookies.
We have given here,
Sample standard deviation=2.32
Sample size =70
Degree of freedom =n-1=69
Level of significance given =1-0.99=0.01
Chi square critical value for lower tail=42.494
Chi square critical value for upper tail=102.996
We can use here confidence interval formula for population standard
deviation
=(1.8989,2.9563)
Lower confidence limit for population standard
deviation=1.8989
Upper confidence limit for Population standard
deviation=2.9563