Samuel works for the local YMCA. He believes that retired adults who participate in group exercises at the YMCA have lower blood pressure than those who participate in exercise on their own. He thinks that not only does the exercise help them physically, butsocializing with others helps lower their stress. If this is so, he would like to institute more group classes for retirees.

Research question:

Null hypothesis:

Alternate hypothesis:

Based on the following alternate hypotheses, should the researcher use a one- or two-tailed statistical test?