平均数、方差、标准差是统计初步中重要基础慨念,它有两个简单、易懂的性质: 若n个数据x_1、x_2、…、x_n的平均数是x,方差为s~2,标准差为s,那么: 1.n个新数据x_1+a、x_2+a、…、x_n+a的平均数是x+a,而方差和标准不变; 2.n个新数据kx_1、kx_2、…、kx_n(k The average, variance, and standard deviation are important basic concepts in statistics. It has two simple and understandable properties: If the average number of n data x_1, x_2, ..., x_n is x, the variance is s~2, The standard deviation is s, then: 1. The average number of n new data x_1+a, x_2+a, ..., x_n+a is x+a, and the variance and standard are unchanged; 2.n new data kx_1, kx_2 ,...,kx_n(k