here's one:-) "Sente, Violet, Scarlett and Kurt have spent the day hiking in the hills to the south of the city. On their way home is a rickety old bridge that's only strong enough for two of them to be on it at the same time. The light is fading fast and so they need to use a flashlight every time they make a crossing. The bridge is too long and narrow to throw the flashlight across, so someone will always have to carry it back and forth. What's more, Sente was injured earlier in the day and will take 10 minutes to cross the bridge. Scarlett can cross in 5 minutes, Kurt in 2 minutes and Violet in just 1 minute. A storm is brewing and they can't waste any time. Kurt thinks for a moment and claims they can all cross the bridge in just 17 minutes. How?"