Let both the costs and the weights be measured on a floating point scale from 0.0 to 1.0. In the case of this work,
the comparison groups are the criteria by which apps are evaluated, costs (positive in this context) are the values that
an app scores for each criterion, and utilities are the weightings applied to the costs. The cost-utility-function applied
to a single app is simply the sum of products between scores and weights. The result is the overall weighted score that
the app has and that indicates the degree of its utility.