求助数学题一道~~做PREP遇到的··

nicholas81 · 发表于 2012-8-6 08:36:59

shipment number of defective chips in the shipment total number of chips in the shipment
s1 2 5,000
s2 5 12,000
s3 6 18,000
s4 4 16,000
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. Whaat is the expected number of defective chips in a shipment of 60,000 chips?
答案是20~求解~·······我算得21··没有答案··

jsmart · 发表于 2012-8-6 09:11:20

一共有2+5+6+4=17个defective chips；total chips 是5000+12000+18000+16000=51000

（60000/51000）*17=20

miaomiaod · 发表于 2012-8-6 09:14:13

·貌似是（（2+5+6+4）/（5000+12000+18000+16000））*60000

求助数学题一道~~做PREP遇到的··

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