 For example, consider the premises [The number of eggs in the nest is between 1 and 10] and [The number of eggs in the nest is odd], along with the conclusion [The number of eggs in the nest is prime], in which only the idea [the number of eggs in the nest] is considered variable in each of the propositions. Of the admissible substitutions, four make both premises true and, of those four, three make the conclusion true as well. Thus the degree of validity of the conclusion relative to the premises and the specified variable is .75. We can also think of this as a relation between the forms ‘A is between 1 and 10’, ‘A is odd’, and ‘A is prime’. 