CHALLANGE #2

Four people (A.B,C,D) WANT TO CROSS A BRIDGE AT NIGHT. tHERE IS ONLY ONE Torch in order to cross the bridge. Every time there could be at least two people crossing the bridge. The time for A,B,C,D to cross the bridge are 1,2,5,10 minutes respectively. SO what is the minimum time for all of them to cross the bridge?

every bodi's afraid to ans dis?--hahaha

the respective time for all of them is 5 mins.

WRONG!

it's 17!!--haha-all of u got wrong!!--

17 doesn't make sense. Explain that?

I think it's 10.

Yes, it's 10 if AT LEAST 2 people can cross at the same time. I think she meant at most. In that case,
Person A & B cross the bridge with torch in 2 minutes. Then A goes back across to C&D to return torch, which takes one minute. Then C&D cross together with torch which takes 10 minutes. then B goes back across with torch taking 2 minutes, and A&B walk across together once more... another 2 minutes. Total, 17 minutes like Secret said.

Don't ask, riddles are my thing

wow!!--u r good!!--

thank you---

10