Jose and Maria run a small surf-board shop in Rincon. They must order surf-boards for the coming season. Orders for the surf-boards must be placed in quantities of twenty (20). The cost per surf-board is $70 if they order 20, $67 if they order 40, $65 if they order 60, and $64 if they order 80. The surf-boards will be sold for $100 each. Any surf-boards left over at the end of the season can be sold (for certain) at $45 each. If Jose and Maria run out of surfboards during the season, then they will suffer a loss of "goodwill" among their customers. They estimate this goodwill loss to be $5 per customer who was unable to buy a surf-board. Jose and Maria estimate that the demand for surf-boards this season will be 10, 30, 50, or 70 surf-boards with probabilities of 0.2, 0.4, 0.3, and 0.1 respectively.
Explain how many surf-boards they should buy, based on the Expected Value Criterion, Minimax Criterion and the Maximax criterion. Which is more reliable and why?