回复：转帖一道看似简单的“超超难”智力题

Person 1,2,3 take the car first, while 4,5 walk.

T1 is time takes for the car to travel to the destination and come back to pick up the slowest walker (person 4 at speed of 4m/s).

L1 is the distance walked by person 4 during T1. L2 is the distance traveled by the car during T1

L1 = 4 x T1, L2 = 10 x T1, and L2 = 1000 + (1000 - L1)

10 x T1 = 2000 - 4 x T1

16 x T1 = 2000 ==> T1 = 2000 / 16 = 1000/8 = 125

T2 is the time the car travled after picking up the walkers,

4 x T1 + 10 x T2 = 1000

4 x 125 + 10 x T2 = 1000

500 + 10 x T2 = 1000

10 x T2 = 500 ==> T2 = 50

T = T1 + T2 = 175

所有跟帖： 

• 三元一次方程 + 普通力学 -珠峰- ♂ (1377 bytes) () 10/17/2008 postreply 19:54:25

• 五人不能同时到达终点？mean not a perfec solution -xyz100- ♂ (0 bytes) () 10/23/2008 postreply 11:22:35