A production line makes units with a mean weight of 80 g and standard deviation of 5 g. What is the probability that a sample of 100 units has a mean weight of less than 79 g?
A machine makes parts with a variance of 14.5 cm in length. A random sample of 50 parts has a mean length of 106.5 cm. What are the 95% and 99% confidence intervals for the length of parts?