In the puzzle Four people on a Bridge we met four people who needed to cross a bridge at night. In this puzzle, there are five people who must cross two sequential bridges at night. As in the original puzzle, there are some hindrances:

The bridges can only support two people crossing at a time.

Each person has a different speed in which they can cross: 10 minutes, 7 minutes, 5 minutes, 2 minutes, and 1 minute.

They have only two flashlights to share among them.

What is the shortest amount of time it will take for all five people to cross both bridges?

rememvber there are no 2 cars going the same speed so that each bridge requires only one light

the slowerone gets the light of each pair as light radiates and the slowere one will illuminate the path of the faster one (we dont know how long the bridges are ir how bright the light).

with the 10 going with 7   the 5 going with 2 etc.

here is the sequence(an L next to the number means the one with the light. side A is the origin point, side B is the destination):

at A   10L goes with 7 as 5L goes with 2  leaves to go to B 

at 5 mintutes at B  5 hands the light to 2  2L leaves to go to A other side

at 7 minutes 2L is at A with 1 (7L arrives at B) 2L and 1 leave for B

at 8 minutes 1 is at B

at 9 minutes 2L is at B

at 10 Minutes 10L is at B

 

 

 

 

Posted by Rich on 2005-09-23 08:03:50