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 60,000 chips?
(A) 14
(B) 20
(C) 22
(D) 24
(E) 25
Shipment Number of Defective Chips.. Total number of Chips.. S1 2 5,000 S2 5 12,000 S3 6 18,000 S4 4 16,000
这道题的意思是专家预计未来的shipment要满足 number of defective chips与 total number of chips的比例和S1,S2,S3,S4这几次shipment加起来的number of defective chips与 total number of chips的比例相同。那么 S6 number of defective chips total number of chips X 60,000 S1+S2+S3+S4 2+5+6+4=17 5,000+12,000+18,000+16,000=51,000 X/60,000=17/51,000 X=20
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发表于 2010-8-15 00:00:28
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