7. The pH of blood for normal healthy adults is generally accepted to be = 7.4. A new drug being tested is thought to decrease the pH to unhealthy low levels. A random sample of 36 patients took the drug over a 5-month period. Blood tests showed that the sample mean was 6.7 with a sample standard deviation of 1.9. Using = 0.01, test the claim that the drug has lowered the mean pH level.