A company produces a women's bowling ball that is supposed to weigh exactly 14 pounds. Unfortunately, the company has a problem with the variability of the weight. In a sample of 9 of the bowling balls the sample standard deviation was found to be 0.86 pounds. Construct a 95% confidence interval for the variance of the bowling ball weight.
a. What is the lower limit of the 95% interval? Give your answer to three decimal places.
b. What is the upper limit of the 95% interval? Give your answer to three decimal places.
c. Which of the following assumptions should be checked before constructing the above confidence interval?
the data need to have small variance
the data need to follow a chi-square distribution
the data need to follow a normal distribution
the data need to be right skewed