请教两个ps题

passerr

15. In a certain game, a large container is filled with red, yellow, green, and blue beads worth, respectively, 7, 5, 3, and 2 points each. A number of beads are then removed from the container. If the product of the point values of the removed beads is 147,000, how many red beads were removed?
   (A) 5
   (B) 4
   (C) 3
   (D) 2
   (E) 0
我觉得red beads的个数可以是1或2或5或7，根据提供选项，可以是A和D，可答案为D，why？

13. At a loading dock, each worker on the night crew loaded  3/4 as many boxes as each worker on the day crew. If the night crew has 4/5  as many workers as the day crew, what fraction of all the boxes loaded by the two crews did the day crew load?
   (A)  1/2
   (B)  2/5
   (C)  3/5
   (D)  4/5
   (E)  5/8
答案是E，我觉得应该是10/3。分析如下：晚上工人load的box数是白天的3/4；晚上工人数是白天的4/5；目前是2人，则在白天load的box数=2/（4/5）/（3/4）=10/3。

看哪位XDJM能指点几招啊！

zhyan

1)147000 = 7^2 * 2^2 * 5^2 * 3 所以应有2个红的
2)设dayworker load X, nightworker load 3/4X
    dayworker y 人, nightworker 4/5y 人
    xy/(xy + 3/4x *4/5y)= 5/8

passerr

先谢谢chyan MM。

1、原来应该是所有point value相乘！而我把相同颜色之间的point value理解成相加，然后再把四个颜色的和相乘了。hehe，还是理解问题。

2、我不明白问的是什么？笨笨的说。也不明白等式如何出来的？麻烦chyan MM再解释。

zhyan

2)问白班工人装的盒子占两班工人装的盒子的百分比

passerr

ic. zhyan, thanks for helping me.