Statement: A district check gate stops every tenth lorry for a full search. Contraband is found in about one search in four hundred. The queue at the gate now stretches two kilometres, and consignments of fish and milk are spoiling in it. Which of the following courses of action follows from the statement?

The statement sets a yield of one in four hundred against a cost borne by every lorry in a two-kilometre queue, so the action that follows is one that raises the yield of a search and lowers what the search costs the innocent. Choosing lorries on papers and information does both. Searching every lorry multiplies the cost tenfold for the same poor yield. Closing the gate abandons the purpose the search exists for. Exempting fish and milk altogether relieves the spoilage but opens a standing door for anyone willing to load a lorry with ice.