[原创] 截止10.3号 11道数学JJ题....一定要看

findjuhl

0. If x is a prime number, is 3xy an even number?
    
(1) x>2
     
(2) y is odd

Answer: C ( from 1, x = 3, 5, 7,11..but we do not know bout y and from stmt 2, y = 1, 3,5,7,9..but we do not know bout x)

1. Is X>Y?

1). (X-Y)/X>0

2). (X^2-Y^2)/X^2>0

2. As the figure above shows, AB=BC=8, CD=2, angle B and angle C are right angle, and

AE=ED=13. What is the area of the ABCDE?

3. A plane traveled k miles in the first 96 minutes of flight time. If it completed the remaining 300 miles of the trip in t minutes, what was its average speed, in mils per hour, for the entire trip?

4. Is the positive integer x an even number?

1). If x is divided by 3, the remainder is 2

2). If x is divided by 5, the remainder is 5

5. What is the tens digit of positive integer x?

1). X divided by 100 has a remainder of 30

2). X divided by 100 has a remainder of 30

6. In the xy-plane, are the points (r,s) and (u,v) equidistance from the origin?

1). r+s=1

2). u=1-r and v=1-s

7. Working independently, Tina can do a certain job in 12 hours. Working independently, Ann can do the same job in 9 hours. If Tina works independently at the job for 8 hours and then Ann works independently, how many hours will it take Ann to complete the remainder of the job?

8. If m and n are positive integers, is m/n a terminal decimal?

1). 90<m<100

2). n=4

9. Mary has 11 more nickels than quarters. How many coins does she have if the total value of her coins is $2.65?

10. A and B are in a line to purchase tickets. How many people are in the line?

1). There are 15 people behind A and 15 people in front of B

2). There are 5 people between A and B

费尽周折弄到的，一定要加精

[此贴子已经被作者于2006-10-4 14:11:20编辑过]

晶莹

楼主真厉害～～～

pfpf

marvelvaliant

谢谢楼主！好强呀，强烈建议加精！

emma姐姐

up

many thx~

盈儿

已经加精,感谢分享~

爱穿越太平洋

大家讨论一下这几道题吧：（已修正！！！）

7、Is X>Y?

1). (X-Y)/X>0

2). (X^2-Y^2)/X^2>0

E

8、A plane traveled k miles in the first 96 minutes of flight time. If it completed the remaining 300 miles of the trip in t minutes, what was its average speed, in mils per hour, for the entire trip?

60*（300+K）/（96+t）  ---这里我忘记了是per hour 

9、Is the positive integer x an even number?

1). If x is divided by 3, the remainder is 2

2). If x is divided by 5, the remainder is 5

E 

10、What is the tens digit of positive integer x?

1). X divided by 100 has a remainder of 30

2). X divided by 100 has a remainder of 30

这个题再议！

11、In the xy-plane, are the points (r,s) and (u,v) equidistance from the origin?

1). r+s=1

2). u=1-r and v=1-s

由1）得s=1-r 又有 u=1-r,所有u=s,同理r=v , 所以，r²+s²=u²+v²  , 所以这两个点到原点的距离是相等的

 12、Working independently, Tina can do a certain job in 12 hours. Working independently, Ann can do the same job in 9 hours. If Tina works independently at the job for 8 hours and then Ann works independently, how many hours will it take Ann to complete the remainder of the job?

（1-1/12 * 8）/（1/9）

 13、If m and n are positive integers, is m/n a terminal decimal?

1). 90<m<100

2). n=4

B

 14、Mary has 11 more nickels than quarters. How many coins does she have if the total value of her coins is $2.65?

设quarter 有X个，0.05（X+11）+0.25X=2.65   X=7  total:7+18=25

15、A and B are in a line to purchase tickets. How many people are in the line?

1). There are 15 people behind A and 15 people in front of B

2). There are 5 people between A and B

E，AB的位置不确定（刚刚忘记改这个题了）

[此贴子已经被作者于2006-10-4 23:01:20编辑过]

wolfie

11、In the xy-plane, are the points (r,s) and (u,v) equidistance from the origin?

1). r+s=1

2). u=1-r and v=1-s

 r+s=1&u=1-r 得到 s=u

同理 r=v

所以 r^2+s^2=u^2+v^2

开根号，即距原点距离相等

选c

15、A and B are in a line to purchase tickets. How many people are in the line?

1). There are 15 people behind A and 15 people in front of B

2). There are 5 people between A and B

由于A和B的位置关系不定，答案不定，选E

爱穿越太平洋

many thx~

emma姐姐

以下是引用findjuhl在2006-10-4 13:40:00的发言：

0. If x is a prime number, is 3xy an even number?
    
(1) x>2
     
(2) y is odd

Answer: C ( from 1, x = 3, 5, 7,11..but we do not know bout y and from stmt 2, y = 1, 3,5,7,9..but we do not know bout x)

  由条件(1)x>2,有x一定为odd, 3x odd, 条件(2)y is odd, 有3xy为odd, 非even, 选C

1. Is X>Y?

1). (X-Y)/X>0

2). (X^2-Y^2)/X^2>0

  由条件(1)有: x-y与x同号, 结论：x可大于y，也可小于y

    由条件(2)有: x^2-y^2>0, 即(x-y)与(x+y)同号, 结论：x可大于y, 也可小于y

    选E

2. As the figure above shows, AB=BC=8, CD=2, angle B and angle C are right angle, and

AE=ED=13. What is the area of the ABCDE?

    s=100

3. A plane traveled k miles in the first 96 minutes of flight time. If it completed the remaining 300 miles of the trip in t minutes, what was its average speed, in mils per hour, for the entire trip?

s=k+300 (miles)

     t=96+t (minutes)=(96+t)/60 hours

     v=s/t=(k+300)*60/96+t

     怎么条件给的这么搞，一会用字母，一会用数字？

4. Is the positive integer x an even number?

1). If x is divided by 3, the remainder is 2

2). If x is divided by 5, the remainder is 5

    

5. What is the tens digit of positive integer x?

1). X divided by 100 has a remainder of 30

2). X divided by 100 has a remainder of 30

    两个条件一样?

    由此条件有：x=100t+30, 十位数为3

6. In the xy-plane, are the points (r,s) and (u,v) equidistance from the origin?

1). r+s=1

2). u=1-r and v=1-s

   若要两点到原点距离相等，则需有r^2+s^2=u^2+v^2，2个条件联立有此式，选C

7. Working independently, Tina can do a certain job in 12 hours. Working independently, Ann can do the same job in 9 hours. If Tina works independently at the job for 8 hours and then Ann works independently, how many hours will it take Ann to complete the remainder of the job?

   tina做8小时，相当于完成了总工作量的2/3，剩下的1/3由ann完成，ann完成总工作9小时，完成1/3需3小时

8. If m and n are positive integers, is m/n a terminal decimal?

1). 90<m<100

2). n=4

   91到99，我想了一下，除4好像都能除尽，不会有循环小数，应该选C吧，还有哪位NN有更好的算法吗？

9. Mary has 11 more nickels than quarters. How many coins does she have if the total value of her coins is $2.65?

   nickel是5美分吧，quarter是啥啊？和美元咋换算？

10. A and B are in a line to purchase tickets. How many people are in the line?

1). There are 15 people behind A and 15 people in front of B

2). There are 5 people between A and B

    分A前B后和A后B前两种情况考虑，总人数不能确定，选E

给出个人意见，XDJM们快讨论一下拉~~

emma姐姐

第8题是B，想了一下，好像随便什么整数除4都除得尽