求教两道PREP数学题

cyberalien

昨晚做了PREP第一套，数学才49，语文34，总分才690。 非常灰心。
有两道数学题还不会解，希望各位牛人帮忙看看：
First:Before being simplified, the instructions for computing income tax in Country R were to add 2 percent of one’s annual income to the average (arithmetic mean) of 100 units of Country R’s currency and 1 percent of one’s annual income. Which of the following represents the simplified formula for computing the income tax, in Country R’s currency, for a person in that country whose annual income is I?
A)50+I/200 ,(B)50+3I/100,(C)50+I/40,(D)100+I/50,(E)100+3I/100
正确的答案是C。我选了E.
Second: 有多少个整数n满足 2^n=n^2？我觉得只有n＝2才能满足。

SkinsRe

2I/100+(I/100 + 100C)/2 =5I/200+50C

2和4都满足啊

加错了 八好意思。。。

flyingbunny

2 percent of one’s annual income
I*2%

the average (arithmetic mean) of 100 units of Country R’s currency and 1 percent of one’s annual income
(100+I*1%)/2

两个一加就好了


second: 有多少个整数n满足 2^n=n^2？我觉得只有n＝2才能满足。
n=2 ，4 均可

cyberalien

THANKS.
第一题的答案是,(C)50+I/40

changyou

690还灰心，那我只有去shi了……