2.12 Exercise and diet are being studied as possible substitutes for medication to lower blood pressure.

Three groups of subjects will be used to study the effect of exercise. Group 1 is sedentary, while group 2 walks and group 3 swims for 1 hour a day. Half of each of the three exercise groups will be on a salt-free diet.

An additional group of subjects will not exercise or restrict their salt, but will take the standard medication.

Use Z for sedentary, W for walker, S for swimmer, Y for salt, N for no salt, M for medication, and F for medication free.

(a) Show all of the elements of the sample space S.

(b) Given that A is the set of nonmedicated subjects and B is the set of walkers, list the elements of A ∪ B.

(c) List the elements of A ∩ B.