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标题: [求助]数学题一道 [打印本页]
作者: xiangxiang4    时间: 2008-6-18 07:00     标题: [求助]数学题一道

A computer chip manufacturer expects the ratio of the number of defective chips to the total number of chips in all future shipments to equal the corresponding ratio for shipments S1 S2 S3 and S4 combined, as shown in the table above. What is the expected number of defective chips in a shipment of 60000 chips?

对应的图表：   shipment         number of defective chips in the shipment               total number of chips in the shipment

                            S1                                         2                                                                  5000

                            S2                                         5                                                                  12000

                            S3                                         6                                                                   18000

                            S4                                         4                                                                    16000

题目看不明白，谢谢了，哪位 帮个忙

作者: AlphaBeta    时间: 2008-6-18 20:37

题目的意思就是新增加的shipment中，number of defective chips in the shipment与total number of chips in the shipment的比例，与s1,s2,s3,s4的和的比例是相同的，列式子就是：设新增加的shipment中number of defective chips in the shipment为X，则X/60000=(2+5+6+4)/(5000+12000+18000+16000),得到X=20。MM看看对不，加油！
作者: xiangxiang4    时间: 2008-6-19 06:38

明白了     

谢谢



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