prep2 61 求NN解答

61.   6814-!-item-!-187;#058&004969

[?]

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

这道题 用哪方面面的知识？

http://forum.chasedream.com/dispbbs.asp?BoardID=22&ID=146546

之前的讨论贴。。。。

谢谢sea_fairy  你真好 我正在看呢 赫赫

靠 不会这么简单吧。。。。。。。。

(2+5+6+4)/(5000+12000+18000+16000)*60000 = 20

还是不明白哦 为什么这么算。。。。。