It is a dark and stormy night, and foggy, and rather cold. In the middle of nowhere a family battle the elements to get home, they have been walking for miles when they get to 'the great ravine'. For miles in either direction there is only one crossing a very small rickety rope bridge, the family must cross the bridge, your aim is to work out in what order they should cross to get across the bridge in the shortest possible time. Now here are the problems, firstly as the bridge is so old they can only risk two people crossing it at once, also stupidly they only have one torch. No more than two people may cross the bridge at one time and because it is so foggy and there are planks missing from the bridge one of them must be carrying the torch. The ravine is too wide to throw the torch across so someone is going to have a busy night going back and forth.
DATA : There are four members of the family, a boy who is quick who can cross the bridge in only one minute, his sister who is a little slower who takes two, his mother who is slower still at five minutes, and finally the grandmother who is getting on a bit and takes a whopping ten whole minutes to cross.
You may not like the family (who takes their grandmother out for a walk in the middle of a storm?) but they need your help, get them across as fast as you can.