A bacteria-killing enzyme can only be activated in an acidic environment with a pH level of at most 6.7. Thomas has prepared an acidic saline solution for observing the action of the enzyme action of the enzyme. He used a digital pH meter to make 16 measurements of the solution, the sample mean was 6.6 with a sample standard deviation of S=0.2. We assume that the pH meter has a normally distributed error around the correct measure. Can we conclude that the measured pH level is lower than 6.7? Use the significance level of 5%.
