[Vee]

I have been breaking my head trying to solve this puzzle for the past couple of weeks. Any help is appreciated........

A family of 5 needs to cross a bridge. As it is night, they have to carry a lamp while crossing the bridge. Each member of the family takes a specific time to cross the bridge:
1sec, 3sec, 6sec, 8sec and 12sec. The bridge can hold a max. of 2 people. A pair can only walk together at the speed of the slower person. The lamp can last only for 30 sec. How do all of them manage to cross the bridge?

This post has been edited by Vee: 03 November 2009 - 08:59 PM

[trozen2040]

Easy one

Spoiler for In 29 seconds...

Go 1 and 3 (+3)
Returns 3 (+3)
Go 12 and 8 (+12)
Returns 1 (+1)
Go 1 and 6 (+6)
Returns 1 (+1)
Go 1 and 3 (+3)

3+3+12+1+6+1+3 = 29

Maybe someone can do it faster

[K4D]

Spoiler for Answer

1 and 3 go across (3 seconds)
1 goes back (1 second)
12 and 8 go across (12 seconds)
3 goes back (3 seconds)
6 and 1 go across (6 seconds)
1 goes back (1 second)
3 and 1 go across (3 seconds)

3+1+12+3+6+1+3= 29 seconds

[KillerGuns]

Spoiler for Humm...

1 3 6 8 12 ||

1 and 3 cross < 3 sec. Total = 0 + 3 = 3 sec
6 8 12 || 1 3

3 comes back < 3 sec. Total = 3 + 3 = 6 sec
3 6 8 12 || 1

8 and 12 cross < 12 sec. Total = 6 + 12 = 18 sec
3 6 || 1 8 12

1 comes back < 1 sec. Total = 18 + 1 = 19 sec
1 3 6 || 8 12

1 and 6 cross < 6 sec. Total = 19 + 6 = 25 sec
3 || 1 6 8 12

1 comes back < 1 sec. Total = 25 + 1 = 26 sec
1 3 || 6 8 12

1 and 3 cross < 3 sec. Total = 26 + 3 = 29 sec
|| 1 3 6 8 12

[Vee]

Thanks a lot everybody

This post has been edited by Vee: 03 November 2009 - 09:32 PM