请教

sxcream · 发表于 2009-9-22 20:06:00

Q28:

This year Henry will save a certain amount of his income, and he will spend the rest. Next year Henry will have no income, but for each dollar that he saves this year, he will have 1 + r dollars available to spend. In terms of r, what fraction of his income should Henry save this year so that next year the amount he was available to spend will be equal to half the amount that he spends this year?

a:1/r+2

b:1/2r+2

c:1/3r+2

d:1/r+3

e:1/2r+3

Theater M has 25 rows with 27 seats in each row. How many of the seats were occupied during a certain show?

(1) During the show, there was an average (arithmetic mean) of 10 unoccupied seats per row for the front 20 rows.

(2) During the show, there was an average (arithmetic mean) of 20 unoccupied seats per row for the back 15 rows.

这道题目好像是我理解错误了。我选的是D。。。

[此贴子已经被作者于2009/9/22 20:08:25编辑过]

ryan123 · 发表于 2009-9-22 21:03:00

Q28 应该选E

因为每 save 1 dollar, he will have 1+r to spend,

so that he save 1 dollar, he spent 2+2r last year

thus can get that his income is 1+(2+2r)=3+2r

the percentage=1/(3+2r)

第二题应该是选together的吧

sxcream · 发表于 2009-9-23 18:58:00

以下是引用ryan123在2009/9/22 21:03:00的发言：