两道PP题，晕死了。。。

飞行2010

48.6225-!-item-!-187;#058&004914

A certain city with a population of 132,000 is to be divided into 11 voting districts, and no district is to have a population that is more than 10 percent greater than the population of any other district.What is the minimum possible population that the least populated district could have?



(A) 10,700

(B) 10,800

(C) 10,900

(D) 11,000

(E) 11,100

------------------------------------------------------------------------------------------------------------------------------------

【答案】D

【思路】假設the minimum possible population that the least population district could have=x

且假設其他10個voting district的人口 more than10percent

x+(x+0.1x)x10=132,000

x=11,000

这是 破解版的解释，我不太明白，他求出来的是more than 10%的，感觉跟问题相反了呢？再者，为什么要做这样的假设？

62.7564-!-item-!-187;#058&005577

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
这个题理解起来好乱，不明白那个save的钱到底是不是pay里面的？有可能的话给个详细解释吧。
先谢谢你们了。

飞行2010

第一题 题目说任何2个区的之间的人数差额不超过10%,现在就假设刚好相差百分之10算出来就是最少的额，因为比这个人数再少的话就会出现大于百分10的情况。才会有 注解里的那个公式的（这种题你有时间直接代进去算也可以 ^_^）
第二题 take－home pay 是税后工资（T）每月一样，每月从这里面拿出来存起来的钱(S)也一样，T-S就是花掉的钱， 里面说一年存的钱是每月花掉了钱的3倍，就是12S=3(S-T),让你求S/T

-- by 会员 selwyn (2010/2/10 21:15:19)

讲的很清楚，明白了。谢谢，顺便问你一下，我做数学题很多理解不了，可以记住这些表达吗？多做题？还是有什么更好的方法？呵呵。

selwyn

第一题 题目说任何2个区的之间的人数差额不超过10%,现在就假设刚好相差百分之10算出来就是最少的额，因为比这个人数再少的话就会出现大于百分10的情况。才会有 注解里的那个公式的（这种题你有时间直接代进去算也可以 ^_^）
第二题 take－home pay 是税后工资（T）每月一样，每月从这里面拿出来存起来的钱(S)也一样，T-S就是花掉的钱， 里面说一年存的钱是每月花掉了钱的3倍，就是12S=3(S-T),让你求S/T

飞行2010

重新发一遍，那个不太清楚。
48.6225-!-item-!-187;#058&004914

A certain city with a population of 132,000 is to be divided into 11 voting districts, and no district is to have a population that is more than 10 percent greater than the population of any other district.What is the minimum possible population that the least populated district could have?



(A) 10,700

(B) 10,800

(C) 10,900

(D) 11,000

(E) 11,100

------------------------------------------------------------------------------------------------------------------------------------

【答案】D

【思路】假設the minimum possible population that the least population district could have=x

且假設其他10個voting district的人口 more than10percent

x+(x+0.1x)x10=132,000

x=11,000

这是 破解版的解释，我不太明白，他求出来的是more than 10%的，感觉跟问题相反了呢？再者，为什么要做这样的假设？

62.7564-!-item-!-187;#058&005577

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
这个题理解起来好乱，不明白那个save的钱到底是不是pay里面的？有可能的话给个详细解释吧。
先谢谢你们了。