In the Journal of Quality in Maintenance Engineering (Vol. 9, 2003), researchers used an analytic hierarchy process to help build a preferred maintenance organization for ARTHUR, the Norwegian Army's high-tech radar system. The process requires the builder to select alternatives in three different stages (called echelons). In the first echelon, the builder must choose one of two mobile units (regular soldiers or soldiers with engineering training). In the second echelon, the builder chooses one of three heavy mobile units (units in the Norwegian Army, units from Supplier 2, or shared units). Finally, in the third echelon, the builder chooses one of three maintenance workshops (Norwegian Army, Supplier 1, or Supplier 2).
a. How many maintenance organization alternatives exist when choices are made in the three echelons?
b. The researchers determined that only four of the alternatives in part a are feasible alternatives for ARTHUR. If one of the alternatives is randomly selected, what is the probability that it is a feasible alternative?