请教PREP上的几道数学题目。谢谢大家

Q1  A certain of coffee supply store stocks 2 size of the self-stick notepad: blue, green, yellow or pink. The store packs the notepad in package that contain either 3 notepad of the same siz and the same color or 3 notepad of the same size and of 3 different colors. If the order in which the color are packed is not considered, how many different packages of the type described above are packed is not considered, how many different packages of the types described are possible?

A 6            B 8             C 10             D24      E32

为什么选C啊？

Q2. Each employee of Company Z is an employee of either Division X or Division Y, but not both. If each division has some part-time employees, is the ration of the numeber of full-time employees to the number of part-time employees greater for Division X than for Company Y?

(1)The ration of the number of full-time employees to the number of part-time employees is less for Division Y than for Company Z.

(2) More than half of the full-time employees of Company Z are employees of Division X, and more than half of the part-time employee of Company Y are employee of Division Y.

答案选D。两个均可。我只选出了第二个。不知道第一个是为什么。

Q3. When a certain tree first planted, it was 4 feet tall, and the height of the tree increased by a constant amount each year for the next 6 years. At the end of the 6th year, the tree was 1/5 taller than it was at the end of the 4th year. By how many feet did the height of the tree increase each year?

A. 3/10         B.2/5          C.1/2             D.2/3       E6/5

实在没有明白为什么是D.

谢谢大家帮忙解答 啦。

mm第一道题搞错了，找了一下原题应是：

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A certain office supply store stocks 2 sizes of self-stick notepads, each in 4 colors:  blue, green, yellow, or pink.  The store packs the notepads in packages that contain either 3 notepads of the same size and the same color or 3 notepads of the same size and of

3 different colors.  If the order in which the colors are packed is not considered, how many different packages of the types described above are possible?

(A)  6

(B)  8

(C)  16

(D)  24

(E)  32

颜色相同的2*4=8 颜色不同的2*4=8

相加为16，选c

第2题设X部门fulltime a人，parttime b人,Y部门fulltime c人，parttime d人

条件1说a/b < (a+c)/(b+d)    可推出a/b < c/d

第3题设每年长x,第4年底的高度为4+4x,第6年底的高度为4+6x,相差2x.

由题意2x/(4+4x) =1/5  可推出x=2/3

恩。明白了。

谢谢啦：）

原来第三题我理解错了。。汗。