请教一道GMAT PREP的数学题

BELLEIVY · 发表于 2011-12-14 23:40:54

完全不懂这个题目怎么做，请教大牛哦：）谢谢！

BELLEIVY · 发表于 2011-12-14 23:45:35

题目好像不太清晰，在这里写清楚：

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?

14, 20, 22, 24, 25

sdcar2010 · 发表于 2011-12-14 23:48:09

60 = 2*18 + 2*12

defected products = 2* 6 + 2*5 = 22

BELLEIVY · 发表于 2011-12-15 00:50:25

我也是选22的，但答案是20

千与千寻117 · 发表于 2011-12-15 01:12:36

17/51=20/60

sdcar2010 · 发表于 2011-12-15 01:17:47

Sorry. My first answer was wrong.

What the question asks is that "assuming you use the AVERAGE of defect ratios obtained from shipments s1-s4, what would be the number of defects in 60,000 chips."

(2+5+6+4)/(5k + 12k + 18k + 16K) = 1/3k

60k * (1/3k) = 20

BELLEIVY · 发表于 2011-12-15 09:25:12

Thanks very much! 终于明白他问啥了

请教一道GMAT PREP的数学题

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