请教几道我做错的GWD数学题

davidyetao

1. $10,000 is deposited in a certain account that pays r percent annual interest compounded annually, the amount D(t), in dollars, that the deposit will grow to in t years is given by D(t) = 10,000 {1+(r/100)}t.  What amount will the deposit grow to in 3 years?
(1)    D(t) = 11,000
(2)     r =10

我选的是b,答案是d, (1)能算出来吗?

2. If x + y is an integer, is y an integer?
(1)      x – y is an integer.
(2)      x + 2y is an integer.

我选的是d,答案是b， （1）也可以推出y is an integer呀...

3. For a certain race, 3 teams were allowed to enter 3 members each.  A team earned 6 – n points whenever one of its members finished in nth place, where 1 ≤ n ≤ 5.  There were no ties, disqualifications, or withdrawals.  If no team earned more than 6 points, what is the least possible score a team could have earned?

A.    0
B.    1
C.    2
D.    3
E.    4

答案是d, 我觉得d也有可能呀,并不是least possible. 比如,分数组合：(5,0,1) (4,2,0)  (3,0,0)

bqu002

我也感觉第一题第一个算不出来啊，2元一次方程求不出R啊

bqu002

第二题1不可以吧，x=2.5, y=1.5

bqu002

楼组第三题给的例子不就是LEAST POSSIBLE COMBINATION吗？其中有一个队得了三分，再也找不出比三分还少的情况了

chenzih

第一题可以吧。。。T=3 DT=11000

不知道的就是R了吧···把R算出来就可以了啊

bqu002

第一题没说3年的是11000啊，是问知道D(t）=11000能不能求出D(3)

loverrosetear

我来说说。
1题。第一个D(t)=11000意思就是给了个恒等式，t不管等于多少，D(t)都等于11000。
2题。X+Y是interger,选项1，X-Y是interger, 两式想减等于2Y也是interger，但是Y有可能是小数了，所以不能确定。
3题。问的是分数最小能是多少，所以是每个人1分，共3分，并不是问有几种组合。

bqu002

LEAST POSSIBLE COMBINATION不是说最少多少组合，是说这种组合可以出现最小的分数3.

bqu002

还有不管t等于多少D(t)都等于11000不现实啊，除非利息是0

darkangelpp

第一题第一项的意思就是无论什么时候d(t)=11000，所以t=3的时候肯定也是11000咯