两道PREP的数学题，请大家帮忙。谢谢！

julianfl

Shipment	Numbers of defective chips In the shipment	Total number of chips In the shipment
S1	2	5000
S2	5	12,000
S3	6	18,000
S4	4	16,000

 

 

A computer chip manufacture experts 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, S4 combined, as shown in the table above, What is the expected number of defective chips in a shipment.

 

 

A 14

B 20

C 22

D 24

E 25

答案选B，不理解红字部分的意义。谢谢大家。

[此贴子已经被作者于2007-5-4 18:31:26编辑过]

julianfl

Is the integer n odd?

(1)    n is divisible by 3.

(2)    2n is divisible by twice as many positive integers as n.

 

B

第2个条件是什么意思？谢谢大家。

julianfl

真不好意思，第二道题目少打了一行......

非常感谢两位哈。不过真没有想到第一道题目这样做......奇怪：）

看来还要再去看看OG：）