1问题冯占武[河北省围场县卉原中学(068450)]在本刊“互动平台”栏且网上讨论区,曾提出以下问题:某养鱼专业户为估算池塘里鱼的数量,先捕获100条鱼做上记号,然后放回池塘,待标记的鱼完全混合于鱼群后,再捕捞5次(每次重捕后都将捕获的鱼再放回池塘中),记录如下:第1次捕90条,其中带标记的有11条;第2次捕100条,其中带标记的有9条;第3次捕120条,其中带标记的有12条;第4次 1 problem Feng Zhanwu [Weichang County, Hebei Province, the original school (068450]] in the “interactive platform” column and online discussion area, had raised the following questions: a fish farming professional households to estimate the number of fish in the pond, the first capture of 100 The fish should be marked and put back into the pond. After the marked fish is completely mixed with the fish, the fish should be harvested 5 more times (the caught fish will be returned to the pond after each re-capture) and the record is as follows: Catch 90, of which there are 11 marked with; the second capture of 100, of which there are marked with 9; the third capture of 120, of which 12 marked with; the fourth