Letxbe a random variable that represents the pH of arterial plasma (i.e., acidity of the blood). For healthy adults, the mean of thexdistribution is= 7.4.A new drug for arthritis has been developed. However, it is thought that this drug may change blood pH. A random sample of41patients with arthritis took the drug for 3 months. Blood tests showed thatx=8.4with sample standard deviations=3.1.Use a 5% level of significance to test the claim that the drug has changed (either way) the mean pH level of the blood.

What is the value of the sample test statistic? (Round your answer to three decimal places.)