题目

Supplying energy by nuclear power is a new trend in the recent years.However，it may be very dangerous. First，the radioactive material must travel from its place of production to the power station.Although the power stations themselves are strongly built，the containers used for the transport of the materials are not.Normally，only two methods of transport are in use，namely，road and rail.Unfortunately，both of these may have an effect on the general public，since they are sure to pass near，or even through，heavily populated areas. Second，there is a problem of waste.All 将四种个不同颜色的乒乓球，随机放入编号分别为1，2，3，4的四个盒子中（1）求第一个盒子为空盒子的概率（2）求放乒乓球最多的盒子中乒乓球个数ξ的分布列和数学期望E．