求助啊PREP

Yuyiqi · 发表于 2010-2-1 20:08:37

shipment numberof defective chips in the shipment total number of chips in the shipment

S1 2 5000

S2 5 12000

S3 6 18000

S4 4 16000

Acomputer chip manufacturer expects the ratio of the number of defective chips to total number of chips in all future shipments to equal the corresponding ratio for shipments s1 s2 s3 s4 combined, as shown in the table cbove. what is the expected number of defective chips in a shipment of 60000chip?

为什么是20？不会做啊

zhanglu0 · 发表于 2010-2-2 16:31:47

同问！！！

homefu · 发表于 2010-2-2 16:37:19

不知道答案是不是84

homefu · 发表于 2010-2-2 16:38:36

我先说下我的想法：

60000*(2/5000+5/12000+6/18000+4/16000)=84

lw666777 · 发表于 2010-2-2 16:39:32

因为这句话.
the ratio of the number of defective chips to total number of chips in all future shipments to equal the corresponding ratio for shipments s1 s2 s3 s4 combined
它说XX率是和S1,S2,S3,S4全部合起来是一样的..
所以..
D/60,000=(2+5+6+4)/(5000+12,000+18,000+16,000)
D=20

拾海 · 发表于 2010-2-2 16:39:32

题目是说，有一个芯片公司（这个芯片公司不是S1,S2,S3,S4里面的哦，是另外一家，应该是本题关键吧）detective chips比total chips的比率等于S1~S4的综合比率~~
所以，把S1~S4总和起来，求出其综合比率为（5000+16000+12000+18000）/(2+4+5+6)=3000
题干中知道该芯片公司是60000，所以60000/3000=20

lovelunchboy · 发表于 2010-2-2 16:40:56

5000+12000+18000+16000=51000 total shipment
2+5+6+4=17
17/51000 = X/60000
Solve for X, 1/3000=X/60000 => X=20
Read the question carefully: "the ratio of the number of defective chips to total number of chips equal equal the corresponding ratio for shipments s1 s2 s3 s4 combined"

homefu · 发表于 2010-2-2 16:46:37

equal to corresponding ratio combined不是应该把这4种ratio combined起来吗？？？

lovelunchboy · 发表于 2010-2-2 16:50:44

equal to corresponding ratio "FOR" s1 s2 s3 s4 combined => add them all up
equal to corresponding ratio combined => combine the ratio

word game

homefu · 发表于 2010-2-2 16:52:04

额。。。是combined的位置。。。

求助啊PREP

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