请问大家两题PREP 求解答

小吉要加油

Alice
's take-home pay last year was the same each month, and she saved the same fraction of her take-home pay each month.The total amount of money that she had saved at the end of the year was 3 times the amount of that portion of her monthly take-home pay that she did not save.If all the money that she saved last year was from her take-home pay, what fraction of her take-home pay did she save each month?


(A) 1/2

(B) 1/3

(C) 1/4

(D) 1/5

(E) 1/6

D算出来是3/4





At a dinner party, 5 people are to be seated around a circular table.Two seating arrangements are considered different only when the positions of the people are different relative to each other.What is the total number of different possible seating arrangements for the group?(没读懂意思)

(A) 5

(B) 10

(C) 24

(D) 32

(E) 120

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【答案】C

这题怎么看怎么不懂。。。 、、


求解答。。。。

liuyin

1). 设每月收入e，存的部分是f. 则：12fe=3(1-f)e. f=1/5.2). 题目问的其实就是有几种坐法。因为是圆桌，ABCDE和BCDEA是一样的，则：A随意选，B有4种选择，C有3种，D有2种，E有1种。4*3*2*1=24

easttiger2010

1). 设每月收入e，存的部分是f. 则：12fe=3(1-f)e. f=1/5.2). 题目问的其实就是有几种坐法。因为是圆桌，ABCDE和BCDEA是一样的，则：A随意选，B有4种选择，C有3种，D有2种，E有1种。4*3*2*1=24

-- by 会员 liuyin (2012/5/8 18:18:49)

2）中，A随意选是关键。因为题目中提示，相对位置不同，才算是一种坐法。

小吉要加油

谢谢~！！！