关于期望的应用题?问题这样的：设某商品每周的需求量X~U[10,20],而经销商店进货数量为区间[10,20]中的某一整数,商店每销售一单位商品可获利1000元；若供大于求则折价处理,每处理一单位商品

关于期望的应用题?问题这样的：设某商品每周的需求量X~U[10,20],而经销商店进货数量为区间[10,20]中的某一整数,商店每销售一单位商品可获利1000元；若供大于求则折价处理,每处理一单位商品
关于期望的应用题?
问题这样的：
设某商品每周的需求量X~U[10,20],而经销商店进货数量为区间[10,20]中的某一整数,商店每销售一单位商品可获利1000元；若供大于求则折价处理,每处理一单位商品亏损200元；若供不应求,则可从外部调剂供应,此时每单位商品仅获利500元.试求此商店所获利润期望值.
高手来传授下数学知识,感激了.

关于期望的应用题?问题这样的：设某商品每周的需求量X~U[10,20],而经销商店进货数量为区间[10,20]中的某一整数,商店每销售一单位商品可获利1000元；若供大于求则折价处理,每处理一单位商品
我告诉你个简单的方法
建立直角坐标系
在x轴上标记两个点10,20,在坐标平面内做另外两点（10,500）,（20,1000）
注释：（10,500）：表示的是商店没有商品,那么每件获利500元
（20,1000）：表示商店有充足的商品,那么每件获利1000元
连接这四个点,构成一个直角梯形,算这个梯形的面积就是利润期望值
利润期望值=（500+1000）*（20-10）/2=7500

所有可能情况:
{需要货,购入货,收入钱}
{10, 10, 10000},
{10, 11, 9800},
{10, 12, 9600},
{10, 13, 9400},
{10, 14, 9200},
{10, 15, 9000},
{10, 16, 8800},
{10, 17, 8600},
{10, 18, ...

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所有可能情况:
{需要货,购入货,收入钱}
{10, 10, 10000},
{10, 11, 9800},
{10, 12, 9600},
{10, 13, 9400},
{10, 14, 9200},
{10, 15, 9000},
{10, 16, 8800},
{10, 17, 8600},
{10, 18, 8400},
{10, 19, 8200},
{10, 20, 8000},
{11, 10, 11500},
{11, 11, 11000},
{11, 12, 10800},
{11, 13, 10600},
{11, 14, 10400},
{11, 15, 10200},
{11, 16, 10000},
{11, 17, 9800},
{11, 18, 9600},
{11, 19, 9400},
{11, 20, 9200},
{12, 10, 13000},
{12, 11, 12500},
{12, 12, 12000},
{12, 13, 11800},
{12, 14, 11600},
{12, 15, 11400},
{12, 16, 11200},
{12, 17, 11000},
{12, 18, 10800},
{12, 19, 10600},
{12, 20, 10400},
{13, 10, 14500},
{13, 11, 14000},
{13, 12, 13500},
{13, 13, 13000},
{13, 14, 12800},
{13, 15, 12600},
{13, 16, 12400},
{13, 17, 12200},
{13, 18, 12000},
{13, 19, 11800},
{13, 20, 11600},
{14, 10, 16000},
{14, 11, 15500},
{14, 12, 15000},
{14, 13, 14500},
{14, 14, 14000},
{14, 15, 13800},
{14, 16, 13600},
{14, 17, 13400},
{14, 18, 13200},
{14, 19, 13000},
{14, 20, 12800},
{15, 10, 17500},
{15, 11, 17000},
{15, 12, 16500},
{15, 13, 16000},
{15, 14, 15500},
{15, 15, 15000},
{15, 16, 14800},
{15, 17, 14600},
{15, 18, 14400},
{15, 19, 14200},
{15, 20, 14000},
{16, 10, 19000},
{16, 11, 18500},
{16, 12, 18000},
{16, 13, 17500},
{16, 14, 17000},
{16, 15, 16500},
{16, 16, 16000},
{16, 17, 15800},
{16, 18, 15600},
{16, 19, 15400},
{16, 20, 15200},
{17, 10, 20500},
{17, 11, 20000},
{17, 12, 19500},
{17, 13, 19000},
{17, 14, 18500},
{17, 15, 18000},
{17, 16, 17500},
{17, 17, 17000},
{17, 18, 16800},
{17, 19, 16600},
{17, 20, 16400},
{18, 10, 22000},
{18, 11, 21500},
{18, 12, 21000},
{18, 13, 20500},
{18, 14, 20000},
{18, 15, 19500},
{18, 16, 19000},
{18, 17, 18500},
{18, 18, 18000},
{18, 19, 17800},
{18, 20, 17600},
{19, 10, 23500},
{19, 11, 23000},
{19, 12, 22500},
{19, 13, 22000},
{19, 14, 21500},
{19, 15, 21000},
{19, 16, 20500},
{19, 17, 20000},
{19, 18, 19500},
{19, 19, 19000},
{19, 20, 18800},
{20, 10, 25000},
{20, 11, 24500},
{20, 12, 24000},
{20, 13, 23500},
{20, 14, 23000},
{20, 15, 22500},
{20, 16, 22000},
{20, 17, 21500},
{20, 18, 21000},
{20, 19, 20500},
{20, 20, 20000}
总共可能数:121
总共可能的收入总数:1881000
收入的期望:1881000/121=171000/11≈15545.5元

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