说明：  实际的场景，若电梯的最大载客量m=10，设电梯中已有的 客人服从0-10 之间的均匀分布，且电梯中的任意一人在任意一层下的 概率相同，若你在第三层需要乘电梯到第七层，电梯处在第一层，共 8 层。且在每一层等电梯到达他们的目的楼层的客人服从0-3 的均匀分 布此时我们对电梯的运行加一些限 制，即电梯中若有客人未达目的地，电梯不会改变运行方向，求直到 你到达第七层为止，，电梯需停次数的数学期望，并进行计算机模拟验 证。
(The actual scene, if the maximum lift capacity m = 10, the elevator has been designed to obey the guests uniformly distributed between 0-10, and the elevator in any one at any level under the same probability, if you The third layer needs to take the elevator to the seventh floor, the elevator in the first layer, a total of 8 layers. And in each level to reach their goals such as the elevator floor guests subject to the uniform distribution of 0-3 at this time we add some restrictions on the operation of the elevator, the elevator if it has not reached the destination guests, the lift will not change the direction, request until you reach the seventh floor so far, the elevator number of mathematical expectation to be stopped, and the computer simulation.)