5.5 Short-answer questions Jahr in 10. What is the distribution curve of workpieces? What are the physical meaning of o and x? 何谓零件的分布曲线? 和x的物理意义是什么? σ Why is the practical distribution range of normal distribution curve thought to be ±30? What does the 60 represent? 为什么标准正态分布的实际分散范围被认为是±30?60代表什么意思? 12. What are the applications of distribution curve? What are the short comings of distribution curve? 分布曲线法都有哪些用途?分布曲线法有哪些缺点?