代班：2006年12月math原始机经讨论稿3（51-90）12/12纠错更新

phoezi

以下是引用sigrid920在2006-12-7 10:13:00的发言：

51.a guy has three type transactions on his checking account, type A, each time deposit $500 ；type B, each time deduct 400 dollars, type C each time deduct 300 dollars. Ask if this guy made at least 10 times of transactions total in a month.
A) this guy at least made 1 time type A, 1 time type B and 1 times of Type C transaction in a month
B) this guy has $1600 more on his checking account than last month.
C:综合（A）（B）可知最小的次数是500 6次，400 2次，300 2次。

不明白MM的解释~~如果每种一次,-200+500*4=1800>1600, 就5次,不也满足条件(1)(2)吗?

-200是咋回事？

sa009

54.
point A and point B distance is 240 miles, train a goes from A to B,
train b goes from B to A, ask which train is closer to the destination
after 2 hours when they pass each other
A)  during these two hours train a has average speed of 70 miles.
B) train b has average speed of 50 miles for the whole trip.
C:A&B pass each other at 240/(Va+Vb)
AVa+Vb)/2=70 代入上式得知：12/7小时后AB相遇
B:Vb=50 则Va=90 可以算出26/7小时后两车距离目的地的距离

觉得题目有待补充，  条件B不够好， 要是 train b has average speed of 50 miles for the whole trip. 那也肯B第一个小时不动， 后面用了4.8个小时跑完全程
或者 前面每小时100 跑了2小时， 后面再用2.4 小时跑了40 KM， 那样就要选    E

xudbbingo

54. point A and point B distance is 240 miles, train a goes from A to B, train b goes from B to A, ask which train is closer to the destination after 2 hours when they pass each other
A)  during these two hours train a has average speed of 70 miles.
B) train b has average speed of 50 miles for the whole trip.
C:A&B pass each other at 240/(Va+Vb)
AVa+Vb)/2=70 代入上式得知：12/7小时后AB相遇
B:Vb=50 则Va=90 可以算出26/7小时后两车距离目的地的距离

这样看来不是选c吗？a,b都可以。

shiancy

以下是引用phoezi在2006-12-7 8:20:00的发言：

54. point A and point B distance is 240 miles, train a goes from A to B, train b goes from B to A, ask which train is closer to the destination after 2 hours when they pass each other
A)  during these two hours train a has average speed of 70 miles.
B) train b has average speed of 50 miles for the whole trip.
E:A&B pass each other at 240/(Va+Vb)
A:Va=？Va'=70  
B:Vb=50Va

不知道，相遇时间不能确定 （之前看错题了不好意思） 
   

MM，关于这个54题，GG13套中有一套很类似的题目，但是跟JJ原作者描述的条件（a）的意思略有差别。我不知道是因为JJ作者自己的理解还是题目确实是改了，如果这样，说明PEARSON还是很狡猾的，大家要注意题目的不同的表述：

现在贴在这里：

GG13-13 MATH-35

Q35:

Stations X and Y are connected by two separate, straight, parallel rail lines that are 250 miles long.  Train P and train Q simultaneously left Station X and Station Y, respectively, and each train traveled to the other’s point of departure.  The two trains passed each other after traveling for 2 hours.  When the two trains passed, which train was nearer to its destination?

(1)   At the time when the two trains passed, train P had averaged a speed of 70 miles per hour.

(2)
              Train Q averaged a speed of 55 miles per hour for the entire trip.

                  

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

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

C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.

D. EACH statement ALONE is sufficient.

E. Statements (1) and (2) TOGETHER are NOT sufficient.

随题给出的参考答案是C，但是我觉得不对。

请大家讨论吧。

shiancy

以下是引用shiancy在2006-12-7 12:40:00的发言：

MM，关于这个54题，GG13套中有一套很类似的题目，但是跟JJ原作者描述的条件（a）的意思略有差别。我不知道是因为JJ作者自己的理解还是题目确实是改了，如果这样，说明PEARSON还是很狡猾的，大家要注意题目的不同的表述：

现在贴在这里：

GG13-13 MATH-35

Q35:

Stations X and Y are connected by two separate, straight, parallel rail lines that are 250 miles long.  Train P and train Q simultaneously left Station X and Station Y, respectively, and each train traveled to the other’s point of departure.  The two trains passed each other after traveling for 2 hours.  When the two trains passed, which train was nearer to its destination?

(1)   At the time when the two trains passed, train P had averaged a speed of 70 miles per hour.

(2)
     Train Q averaged a speed of 55 miles per hour for the entire trip.

                  

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

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

C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.

D. EACH statement ALONE is sufficient.

E. Statements (1) and (2) TOGETHER are NOT sufficient.

随题给出的参考答案是C，但是我觉得不对。

请大家讨论吧。

BTW://pheozi MM为啥一定要求相遇时间呢?

原JJ不是说after 2 hours WHEN they pass each other ? 而不是说 2 hours after they pass each other啊

sigrid920

73.a group, 44% are males,75% are athletes, 15%femal are not athletes. what is the percent of males who are athletes

                    Male  Female

Athletes          34     41          75

non ath          10      15          25

                      44      56

34/44

what is the percent of males who are athletes这句话到底是问是运动员的男人的%, 还是在男人中有多少%是运动员? 个人觉得是第一个意思, 就不用除44了, 但是对自己没有太大信心, 想问问大家~!!

yangmetal

68题怎么感觉应该是问y＝？

jyou82

以下是引用sa009在2006-12-7 12:26:00的发言：
54.
point A and point B distance is 240 miles, train a goes from A to B,
train b goes from B to A, ask which train is closer to the destination
after 2 hours when they pass each other
A)  during these two hours train a has average speed of 70 miles.
B) train b has average speed of 50 miles for the whole trip.
C:A&B pass each other at 240/(Va+Vb)
AVa+Vb)/2=70 代入上式得知：12/7小时后AB相遇
B:Vb=50 则Va=90 可以算出26/7小时后两车距离目的地的距离

觉得题目有待补充，  条件B不够好， 要是 train b has average speed of 50 miles for the whole trip. 那也肯B第一个小时不动， 后面用了4.8个小时跑完全程
或者 前面每小时100 跑了2小时， 后面再用2.4 小时跑了40 KM， 那样就要选    E

A 一定可以的 因為知道十time = 2 hr,  speed = 70, distance = 240. 如果 A車 前兩小時平均70那兩小時它一定在140 mile 以外. 這樣就夠了 因為總行成是240 mile所以既然A車已走了140 mile 那跟B車(premise = 在兩小時整碰面)就一定走了100 mile 不然就碰不到面... 兩小時整碰面的premise也就不成立了. B 不一定可以因為像樓上說的... 50 /hr 是全程的平均...並不代表前兩小時一定走了100 mile.

jyou82

79、有36％的窗子是吃饭前擦的，50％ of 剩下的是吃饭后擦的，问还有多少没擦？

答案：50％×（1－36％）＝33％

50% x (1-36%) = .50 x .64 = .32 or 32%?

jyou82

69.[z]is the greatest integer less than z. [z]=-1, z的范围

题目给的范围要比我们求的大，到时候只要选在其中的就行，选项我不记得了

(-1,0]

可不可以解釋一下? 我看不懂題目要的是什麼

[此贴子已经被作者于2006-12-7 15:33:24编辑过]