A manufacturer produces piston rings for an automobile engine. It is known that ring diameter is normally distributed with standard deviation (1.001 millimeters. A random sample of 35 rings has a mean diameter of 74.035 millimeters. a. Construct a 99% two sided confidence interval on the mean piston ring diameter. b. How many piston rings would have to be measured for the manufacturer to be 95% condent that the mean diameter from the sample is between "id-.0359 to ?4.0361 oftrue population mean