GWD数学X道求助。。。

夏日飘雪

1 If M is a positive integer, then M^3 has how many digits?
(1) M has 3 digits.
(2) M^2 has 5 digits
_______________________________________________________________-
Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient

lStatement (2) ALONE is sufficient, but statement (1) alone is not sufficient

lBOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.

lEACH statement ALONE is sufficient

lStatements (1) and (2) TOGETHER are NOT sufficient
答案是E

2.Last year in a group of 30 businesses, 21 reported a net profit and
15 had investments in foreign markets. How many of the businesses
did not report a net profit nor invest in foreign markets last year?
(1) last year 12 of the 30 businesses
reported a net profit and had invest-
ments in foreign markets.
(2) last year 24 of the 30 businesses
reported a net profit or invested in
foreign markets, or both.

Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient

lStatement (2) ALONE is sufficient, but statement (1) alone is not sufficient

lBOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.

lEACH statement ALONE is sufficient

lStatements (1) and (2) TOGETHER are NOT sufficient

答案是B，为什么不选D，第一个条件难道说有问题？

3
At a fruit stand yesterday, the price of each apple was $0.10 more than the price of each orange. What was the total revenue from the sale of oranges at the fruit stand yesterday?
(1) The number of oranges sold at the fruit stand
yesterday was 5 more than the number of
apples.
(2) The total revenue from the sale of apples
at the fruit stand yesterday was $15.00

Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient

lStatement (2) ALONE is sufficient, but statement (1) alone is not sufficient

lBOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.

lEACH statement ALONE is sufficient

lStatements (1) and (2) TOGETHER are NOT sufficient

答案是C，我觉得是E。。。。

4.
Yesterday it took a certain plane 3 hours to fly from City A to
City B at an average speed of 400 miles per hour. Today the
same plane flew from City A to City B along the same route at
an average speed of 450 miles per hour. How many more
yesterday than it took today?
A.10
B.15
C.20
D.25
E.30
答案是C，可是我不会做。。。

endlessstory

先回答4
s=vt即路程=速度乘以时间
so 总路程=3*400=1200miles
第二次的时间=1200/450=8/3小时~~~
时间差即，昨天的时间减去今天的时间：3-8/3=1/3小时，即20分钟

endlessstory

1
M是3位数，乘以3以后可以是3位数或者4位数，答案不唯一，所以不充分
M乘以2是5位数，可推出m是4位数或者5位数，也不充分
两个放在一起，即m为4位数，4位数乘以3，不唯一，可以是5位数也可以是4位数，无法得到确切的答案，所以都不充分，选E

endlessstory

3我觉得是E，你的答案确定吗？

欢乐

3我应该是E 因为根据条件1，2，不知道苹果具体的数目及单价均未知，是不足以求出橘子的总价的。

endless1989

2   我觉得·第一个条件可以推出来的··

endless1989

求问？

夏日飘雪

3我觉得是E，你的答案确定吗？

-- by 会员 endlessstory (2010/10/16 17:07:14)

是GWD30套上的题，第25套的题，对了答案，答案是这样写的

夏日飘雪

先回答4
s=vt即路程=速度乘以时间
so 总路程=3*400=1200miles
第二次的时间=1200/450=8/3小时~~~
时间差即，昨天的时间减去今天的时间：3-8/3=1/3小时，即20分钟

-- by 会员 endlessstory (2010/10/16 16:50:24)

原来是求分钟。。。我以为答案是以小时记单位的。。。

明白这题了，谢谢！

yexuu

第一题就是用200和300试一下，第二题和第三题我也怀疑答案有问题