【单选题】已知某灯泡厂生产的灯泡寿命 ,为测定灯泡寿命,现随机抽取9只灯泡,其平均寿命 =1500小时,修正的样本标准差S=100小时,则灯泡的平均寿命 的置信度为95% 的置信区间为( )
【单选题】Where are the man and the woman?
B.
They are in a museum (博物馆).
C.
They are at the cinema.
【简答题】最佳的配送路线应是车辆高效率运行且所需________、距离最短、所需时间最少的线路。
【简答题】A.They are social workers. B.They are in the medical profession. C.They are coal miners. D.They are writers.
【多选题】最佳的配送路线应该是车辆高效率运行而且()。
【简答题】为了了解某种灯泡厂生产的灯泡的使用寿命,应采取( )方式进行调查。
【简答题】Lin Tao and Chen Hai are good friends. They are in the same class. They are in the same team. Lin Tao sits behind Chen Hai. Now it is four o’clock. School is over. They often go to play s after sc...
【单选题】一2周岁女孩,营养生长情况均正常,头围为48cm, 其胸围应是