The Trolley Problem

There is a runaway trolley (or tram as we would say in British English) hurtling down a track. You are standing at a fork in the track next to a lever which controls a set of points. If you do nothing, the trolley will continue along its current path and kill five people. If you flip the lever, the trolley will be diverted along another branch of the track and will only kill one person. What would you do