Four Iowa students are national finalists at a national economics competition in New York this weekend. Dubuque Hempstead High teacher Dennis Schroeder says his kids won preliminary and regional contests in the challenging subject.He says they have to know all about federal reserve policy, demand and supply, government fiscal policy, taxes, spending, international trade, foreign exchange rates and the like. Schroeder says his students are likely to do more than win contests with their economic studies.One student will go to Yale and major in political science and economics there. Schroeder, who teachers history and economics, says there are careers on Wall Street for someone with a good grounding in economics. If the students win the national competition, each will get a five thousand dollar savings bond. For recreation, while they’re in the Big Apple, the kids will tour the Federal Reserve.