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

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.

joywzy

我做DS实在有点疑神疑鬼

不是JJ，是GMAT数学真题。

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?

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。

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 ?

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

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