very simple question, but got to finish it within 30second inclu

very simple question, but got to finish it within 30second including reading the question. if you do not finish this kind of question within couple of seconds, you wont have time to do the hard ones.



A car passes point A driving at a constant rate of 60 km per hour. A second car, traveling at a constant rate of 75 km per hour, passes the same point A a while later and then follows the first car. It catches the first car after traveling a distance of 75 km past point A. How many minutes after the first car passed point A did the second car pass point A?

所有跟帖： 

• 如果还有人怀疑你对数学的狂热爱好，那人一定是瞎子：） -毕小珠-- ♀ (0 bytes) () 04/17/2010 postreply 18:21:03

• 不是狂热，就有一点而已。：）） -A-Momy- ♀ (0 bytes) () 04/17/2010 postreply 18:21:55

• 嗯，一妈这两天是突然猛往这贴数学题，希望不是因为。。。：） -听听意见- ♀ (0 bytes) () 04/17/2010 postreply 18:49:17

• any one gets the solution -A-Momy- ♀ (78 bytes) () 04/17/2010 postreply 18:26:31

• 俺彻底晕菜。 -gossipgirl8- ♀ (0 bytes) () 04/17/2010 postreply 18:33:46

• 25 minutes? -gossipgirl8- ♀ (0 bytes) () 04/17/2010 postreply 18:38:32

• no -A-Momy- ♀ (0 bytes) () 04/17/2010 postreply 18:41:20

• 这题写的不好。 -A-Momy- ♀ (0 bytes) () 04/17/2010 postreply 18:40:42

• 你自己编的题啊？ 俺N年没解数学题了。 娃大了可能要开始练练手。 -gossipgirl8- ♀ (0 bytes) () 04/17/2010 postreply 18:42:57

• 回复：any one gets the solution -lucasia- ♀ (132 bytes) () 04/17/2010 postreply 20:20:51

• no idea..:)) -A-Momy- ♀ (0 bytes) () 04/17/2010 postreply 20:34:11

• no -A-Momy- ♀ (0 bytes) () 04/17/2010 postreply 18:42:00

• ask your son. :)) -A-Momy- ♀ (76 bytes) () 04/17/2010 postreply 18:50:06

• 非常好！ -A-Momy- ♀ (0 bytes) () 04/17/2010 postreply 19:43:11

• 回复：very simple question, but got to finish it within 30second in -byrbyw- ♀ (10 bytes) () 04/17/2010 postreply 18:57:13

• 15 -小睿儿- ♀ (0 bytes) () 04/17/2010 postreply 18:58:46

• 15min is right and the point is to do it within a few seconds. : -A-Momy- ♀ (73 bytes) () 04/17/2010 postreply 19:04:20

• 赶时间的话连式子都不能列，就“因为“”所以“的往下 -trivial- ♀ (238 bytes) () 04/17/2010 postreply 19:47:03

• lol... -A-Momy- ♀ (131 bytes) () 04/17/2010 postreply 20:03:18

• Yes, exactly! -trivial- ♀ (0 bytes) () 04/17/2010 postreply 20:05:23

• so there is no paper needed. :)) or no hand needed. -A-Momy- ♀ (90 bytes) () 04/17/2010 postreply 20:09:10

• so I didn't :) -trivial- ♀ (0 bytes) () 04/17/2010 postreply 20:23:25

• 让用草稿纸么？还是得在脑子里空转？ -trivial- ♀ (238 bytes) () 04/17/2010 postreply 19:32:54

• 这种题目是这儿几年级学生做的？ -钱串儿- ♀ (76 bytes) () 04/17/2010 postreply 19:39:33

• 在国内差不多是三，四年级的应用题。 -trivial- ♀ (116 bytes) () 04/17/2010 postreply 19:56:43

• mathcounts goes beyond 8th grade math. -A-Momy- ♀ (248 bytes) () 04/17/2010 postreply 19:46:33

• Do they still have competitions beyond 8th grade? -trivial- ♀ (206 bytes) () 04/17/2010 postreply 19:51:35

• i do not think this question is not stated clearly. -A-Momy- ♀ (386 bytes) () 04/17/2010 postreply 19:57:04

• I guess my real question is, how does Mathcounts -trivial- ♀ (301 bytes) () 04/17/2010 postreply 20:03:39

• I never thought how mathcounts is related to 爬藤. -A-Momy- ♀ (142 bytes) () 04/17/2010 postreply 20:12:06

• 噢，磨把牛刀去杀鸡！ -trivial- ♀ (0 bytes) () 04/17/2010 postreply 20:25:52

• 15 -猪兔同龙- ♂ (0 bytes) () 04/17/2010 postreply 21:41:43