Supposed that we wish to test H₀: = 80 versus H_a: > 80, where the population standard deviation is known to equal 20. Also, suppose that the sample of 100 measurements randomly selected from the population has a mean equal to 85.

1. Calculate the value of the test statistic z.
2. By comparing z with a critical value, test H₀ versus H_a at = 0.05.
3. Calculate the p-value for testing H₀ versus H
4. Use the p-value to test H₀ versus H_a at each of = 0.10. 0.05, 0.01, and 0.001