已知 5 件产品中有 2 件次品, 其余为合格品. 现从这 5 件产品中任取 2 件, 恰有一件次品的概率为
设 5 件产品中 3 件合格品分别为 $A_{1}, A_{2}, A_{3}, 2$ 件次品分别为 B1, B2, 则从 5 件产品中任取 2 件的所有基本事件为 $\left\{A_{1}, A_{2}\right\},\left\{A_{1}, A_{3}\right\}$, $\left\{A_{1}, B_{1}\right\},\left\{A_{1}, B_{2}\right\},\left\{A_{2}, A_{3}\right\},\left\{A_{2}, B_{1}\right\},\left\{A_{2}, B_{2}\right\},\left\{A_{3}, B_{1}\right\},\left\{A_{3}, B_{2}\right\},\left\{B_{1}, B_{2}\right\}$ 共 10 个, 其中恰有一
件次品包含的基本事件为 $\left\{A_{1}, B_{1}\right\},\left\{A_{1}, B_{2}\right\},\left\{A_{2}, B_{1}\right\},\left\{A_{2}, B_{2}\right\},\left\{A_{3}, B_{1}\right\},\left\{A_{3}, B_{2}\right\}$, 共 6 个, 故所求的概率为 $P=\frac{6}{10}=0.6$.

答案: B