An experiment is conducted to show that blood pressure can be consciously reduced in people trained in a "biofeedback exercise program." Six (6) subjects were randomly selected and the blood pressure measurements were recorded before and after the training. The difference between blood pressures was calculated (after − before) producing the following results: xd = −10.2, sd = 8.4. Using the data, test the hypothesis that the blood pressure has decreased after the training. What is the distribution for the test?