【一道关于方差的经济学问题!45%chancethatmarketXwillendtheyearat80andmarketYat47,55%chancethatmarketXwillendtheyearat104andmarketYat50.TheCovariance(协方差）betweenthesemarketsis请附具体解题步】

问题：【一道关于方差的经济学问题!45%chancethatmarketXwillendtheyearat80andmarketYat47,55%chancethatmarketXwillendtheyearat104andmarketYat50.TheCovariance(协方差）betweenthesemarketsis请附具体解题步】

答案：↓↓↓

丁吉豫的回答：

网友采纳　　协方差的运算公式：加和p(x-x平均)（y-y平均）所以本题中,x平均=0.45*80+0.55*104=93.2y平均=0.45*47+0.55*50=48.65协方差=0.45*（80-93.2）*（47-48.65）+0.55*（104-93.2）*...