It is nighttime, There is a bridge. There are 4 girls with a flashlight who need to get to the other side safely. If 1st girl takes 1min,2nd girl takes 2mins, 3rd girl takes 5mins, 4th girl takes 10mins. They need to cross in 17 mins, or the bridge will break. They need to get across and back in under 17mins. In pairs, only the longest time counts. How is it possible to get all 4 girls across and back with the above conditions? HELP!
