Wasserman (1989) studied a process for the manufacturing of steel bolts. Historically, these bolts have a mean thickness of 10.0 mm and a standard deviation of 1.6 mm. In a quality check the engineer has a sample of 5 randomly selected and measured.
Assuming a near normal distribution what are the mean and standard deviation of the sample mean of these quality checks?
A recent sample of five wafers yielded a sample mean of 10.4 mm. Find the probability of observing such a mean of something larger based on the historic mean and standard deviation.
90% of the means taken from samples of 5 should be smaller than what value?