请教几道数学题

joywzy

5. A certain car traveled from one town to another without stopping. What was the car's average speed for the trip ?
(1) The car traveled the 90-mile trip in 2 hours.
(2) The car traveled the first 40 miles of the trip in 1 hour.

答案:A,我选E
我认为题目没有告诉距离,时间或者是是否匀速前进

2. The price of a television set was reduced by 25 percent. What was its original price?
(1) The reduced price was $187.50.
(2) The original price exceeded the reduced price  by more than $60.00.

答案是A,我选D
设original price 为X
(1) => X*75%=187.5
(2) => X-75%X=60
两者均满足
难道more than $60.00.理解为>60

7. What was Jean's insurance premium in 1995?
(1) The ratio of Jean's insurance premium in 1995 to  her insurance premium in 1994 was  .
(2) Jean's insurance premium in 1995 was 20 percent more than her insurance premium in 1994.
答案:E,我选C
设1995为X,设994为Y
(1)X/Y=6/5
(2)X-Y=20%X 两者连立,可得X
我什么地方不对吗?


9. The figure above shows the present position on a radar screen of a sweeping beam that is rotating at a constant rate in a clockwise direction. In which of the four quadrants will the beam lie 30 seconds from now ?
(1) In each 30-second period, the beam sweeps through  3.690°
(2) r = 40
答案:A,我选C

17. Every member of a certain club volunteers to con-tribute equally to the purchase of a $60 gift certificate. How many members does the club have?
(1) Each member's contribution is to b$4.
(2) If 5 club members fail to contribute, the share of  each contributing member will increase by $2.
答案是D
这题是什么意思

nobodytest

5. A certain car traveled from one town to another without stopping. What was the car's average speed for the trip ?
(1) The car traveled the 90-mile trip in 2 hours.
(2) The car traveled the first 40 miles of the trip in 1 hour.

A 告诉距离,时间

2. The price of a television set was reduced by 25 percent. What was its original price?
(1) The reduced price was $187.50.
(2) The original price exceeded the reduced price by more than $60.00.
D

7. What was Jean's insurance premium in 1995?
(1) The ratio of Jean's insurance premium in 1995 to her insurance premium in 1994 was .
(2) Jean's insurance premium in 1995 was 20 percent more than her insurance premium in 1994.
E   (2)(X-Y)/Y=20%X

9. The figure above shows the present position on a radar screen of a sweeping beam that is rotating at a constant rate in a clockwise direction. In which of the four quadrants will the beam lie 30 seconds from now ?
(1) In each 30-second period, the beam sweeps through 3.690°
(2) r = 40
no chart, but A sounds better

17. Every member of a certain club volunteers to con-tribute equally to the purchase of a $60 gift certificate. How many members does the club have?
(1) Each member's contribution is to b$4.
(2) If 5 club members fail to contribute, the share of each contributing member will increase by $2.
$60均摊,求人数.  A
---------------------------
Open to discuss

joywzy

5,并没有告诉the distance from one town to anther,和时间,也没有告诉是否匀速前进

7,(2) Jean's insurance premium in 1995 was 20 percent more than her insurance premium in 1994.
(2)(X-Y)/Y=20%X 对吗?

9,图是R为从X轴开始的在第一象限的一个角,我贴不上来了,只好写了
.
17,如果按你的理解,那么答案是D
(2)设人数为N,60/(N-5)=60/N+2

卧室春竹

呵呵
偶觉得如果第一题  出题的人的想法是两个城市之间的距离就是90

第7题 2 应该是 X=(1+20%)Y ?

yvonnezenith

to joy
第一题选A.恐怕你钻牛角尖了。
第二替我觉得>60，如果正好60，不用加more than就说得通。
第三题，我觉得1和2条件一样，得出的结果就是x=6/5*y.
第四题，是转3690度吗？如果是的，3690/360得10余90，在第一象限内顺时针转90度，除点本来就再坐标轴上，否则一定在第四象限。不知道条件2里的r值得是什么。
第五题，答案是D.
假设人数为x,人均交y,有题目本身就可以得到：x*y=60
根据条件2，(x-5)*(y+2)=60，自然可以算出x=15。

nobodytest

5,并没有告诉the distance from one town to anther,和时间,也没有告诉是否匀速前进 --------------------- E the distance is given but the time is uncertain <=2hrs 7,(2) Jean's insurance premium in 1995 was 20 percent more than her insurance premium in 1994. (2)(X-Y)/Y=20% a mistake 17,如果按你的理解,那么答案是D (2)设人数为N,60/(N-5)=60/N+2 agree --------------------------------- Open to discuss BTW, are these the latest JJ?

joywzy

我做DS实在有点疑神疑鬼

不是JJ，是GMAT数学真题。

nobodytest

7,(2) Jean's insurance premium in 1995 was 20 percent more than her insurance premium in 1994.
E. (2)(X-Y)/Y=20% => B is insufficient, both A and B together are insufficient, so E. hope you understand this time.