Question: Let x be a random variable that represents the ph of arterial plasma. For healthy adults the mean of x distribution is mu=7.4. A new drug for arthritis has been developed. However it is thought that this drug may change blood ph. A random sample of 31 patients with arthritis took the drug 3 months . Blood tests showed the average ph to be mean =8.1with sample standard deviation s=1.9. Use a 5% level of significance to test the claim that the drug has changed (either way) the mean ph level of the blood.