x is a random variable that represents ph of arterial plasma, the mean of the x distribution is 7.

x is a random variable that represents ph of arterial plasma, the mean of the x distribution is 7.4. a random sample of 33 patients with arthritis took the drug for 3 months blood test showed an average of pH to be Xbar=8.1 with sample standard deviation s=0.6. Use a 5% level of significance to test the claim that the drug has changed(either way) the mean pH level of the blood.