There are 4 people going through a bridge. One takes 5-min, one takes 1-min, one takes 2-min, and one takes 10-min. And only two people can go through once. Question: what is the shortest time that 4 people cross the bridge?
Its a common puzzle but your question is incomplete. the two people can only cross the bridge by using a torch. So one guy will always hold the torch. Solution: first 10 & 1 will go and then 1 will return back. - total time = 10+1 = 11 mins then 1 & 5 will go and 1 will return back - total time = 5+1 = 6 mins then 1&2 will go = total time = 2mins total time = 19 mins !!
Correct answer is 17. -> 2+1 :2 10+5 :10 1+2 :2
if no pass, then 12 mins, if someone can pass through another, then 10 mins.
3 mars 2013