An adviser is testing out a new online learning module for a placement test. They wish to test the claim that on average the new online learning module increased placement scores at a significance level of = 0.05. For the context of this problem, _D=_new-_old where the first data set represents the new test scores and the second data set represents old test scores. Assume the population is normally distributed.

H₀: _D = 0

H₁: _D < 0

You obtain the following paired sample of 19 students that took the placement test before and after the learning module: