一道Prep数学，没看懂题

liangruichao · 发表于 2010-5-30 12:57:13

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

A computer chip manufacturer expects the ratio of the mumber of defective chips to the total mumber 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?

A. 14
B. 20
C. 22
D. 24
E. 25

答案是B。这道题没有看懂，不知道S1到S4什么关系。。。请大家帮忙说说。

zhuteam1 · 发表于 2010-5-30 16:31:14

就是说未来生产的shipment的坏芯片数/总芯片数，要等于S1,S2,S3,S4合在一起的坏芯片数/总芯片数，即x/60000=(2+5+6+4)/(5000+12000+18000+16000)，得20

liangruichao · 发表于 2010-5-31 18:25:49

Thanks

一道Prep数学，没看懂题

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