Matched or Paired Samples · Exercise 13

An experiment is conducted to show that blood pressure can be consciously reduced in people trained in a “biofeedback exercise program.” Six subjects were randomly selected and blood pressure measurements were recorded before and after the training. The difference between blood pressures was calculated (after - before) producing the following results: ${\left(\bar{x}\right)}_d$ = −10.2 s_d = 8.4. Using the data, test the hypothesis that the blood pressure has decreased after the training.
The distribution for the test is:

(a) t_5
(b) t_6
(c) N(−10.2, 8.4)
(d) N(−10.2, $\frac{8.4}{\sqrt{6}}$)

Its source prints no answer for this problem, so there's nothing to check against.

OpenStax, Introductory Business Statistics 2e · §10.6 Matched or Paired Samples · Exercise 13