解答排列组合应用题时,最容易犯的错误是重复和遗漏,遗漏大多比较明显;而重复则往往较为隐蔽,不易察觉.下面通过例题剖析一些常见重复计算错误,研究失误的原因,寻求纠正和预防的办法,以飨读者.例1 产品检验时,常以产品中抽出一部分进行检查,如果100件产品中有2件次品,抽出的3件至少有1件是次品的抽法有多少种?(高中代数第三册P_(65)例4) When arranging combinatorial applications, the most common mistakes are repetitions and omissions. The omissions are mostly obvious. The repetitions are often more subtle and difficult to detect. The following examples analyze some common repetitive calculation errors, study the causes of errors, and seek corrections. The method of prevention is for the readers. Example 1 In the inspection of products, a part of the product is often inspected. If there are 2 defective products in 100 products, at least 1 of the 3 products extracted is the number of defective products. Species (high school algebra third volumes P_(65) cases 4)