As in Problem 1-18, state the appropriate economic criterion for each of the following situations.

(a) The engineering school held a raffle of an automobile with tickets selling for'50~each or three for $1. When the students were selling tickets, they noted that many people had trouble deciding whether to buy one or three tickets. This indicates the buyers' criterion was _'

(b) A student organization bought a soft-drink machine for use in a student area. There was considerable discussion over whether they should set the machine to charge Sot, 75~, or $1 per drink. The organization recognized that the number of soft drinks sold would depend on the price charged. Eventually the decision was made to charge 75~. Their criterion was.

(c) In many cities, grocery stores find that their sales are much greater on days when they have advertised their special bargains. However, the advertised special prices do not appear to increase the total physical volume of groceries sold by a store. This leads us to conclude that many shoppers' criterion is _'

(d) A recently graduated engineer has decided to return to school in the evenings to obtain a master's degree. He feels it should be accomplished in a manner that will allow him the maximum amount of time for his regular day job plus time for recreation. In working for the degree, he will