the diameter of a particular precision ball bearing has a target value of 20 millimeters (mm). suppose the bearing diameters have a normal distribution with a standard deviation of 0.065 mm. when a shipment of bearings arrives, the consumer takes a sample of 25 bearings from the shipment and measures their diameters to see if it meets the target value, and finds the mean to be 20.15 mm. perform this hypothesis test at the 5% significance level using the critical value approach. 9. the employment and training administration reported that the u.s. mean unemployment insurance benefit was $238 per week. using a sample of 100 individuals from the state of virginia, the mean weekly unemployment insurance was $231 with a sample standard deviation of $80. assuming that weekly unemployment insurance benefits are approximately normally distributed, use a statistical hypothesis test at a 5% significance level to determine if there is sufficient statistical evidence to claim that the mean weekly unemployment insurance benefit in virginia is below the national average.
