Abstract: Based on the analysis of the traditional decision making models,such as Friedman and Hanssman-Rivett,this paper proposes more practical decision making target.Further more,from this newly obtained decision making target,the formula on average numbers or the number of participators for bidders are obtained,which is quite different from the traditional methods according to the historical data or estimations.

Key words: bidder, number of bidders, expected profits, decision-making target, winning probability