A researcher suspects the mean trough (the lowest dosage of medication required to see clinical improvement of symptoms) level for a medication used to treat arthritis is different than was previously reported in other studies

A researcher suspects the mean trough (the lowest dosage of medication required to see clinical improvement of symptoms) level for a medication used to treat arthritis is different than was previously reported in other studies. Previous studies found the mean trough level of the population to be 3.7 micrograms/mL. The researcher conducts a study among 93 newly diagnosed arthritis patients and finds the mean trough to be 4.1 micrograms/mL with a standard deviation of 2.4 micrograms/mL. The researcher wants to test at the 5% level of significance if the trough is different than previously reported or not. Z statistics will be used.

Complete Step 3 of hypothesis testing:  Set up decision rule