5. Find the 95% confidence interval for the standard deviation for the lifetime of disposable batteries if a sample of 16 disposable camera batteries has a standard deviation of 2.1 months. Assume the variable is normally distributed. 6. A quality control engineer of a company that manufactures PVC pipe wants to estimate the standard deviation of the diameter of their product. Hence, they randomly select 10 pipes from a batch and measure its inside diameter using a digital caliper. The data is as shown, Table 1. Diameter measured in inches. 2.005 2.003 1.999 2.002 2.009 1.998 2.001 2.005 2.002 1.999 2.003 2.009 Determine the 99% confidence interval for the standard deviation of the diameter of the pipe