An experimental study of this problem is discussed at 'the trolley problem revisited'
3a
A trolley (tram) is running out of control down a track. In its path are five people who have been tied to the track by a mad philosopher. Fortunately, you can flip a switch which will lead the trolley down a different track. Unfortunately, there is a single person tied to that track.
Should you flip the switch?
3b.
As before, a trolley(tram) is hurtling down a track towards five people. You are on a bridge under which it will pass, and you can stop it by dropping a heavy weight in front of it. As it happens, there is a very fat man next to you - your only way to stop the trolley is to push him over the bridge and onto the track, killing him to save five.
Should you push him?
3c.
As before, a trolley(tram) is hurtling down a track towards five people. As in the first case, you can divert it onto a separate track. On this track is a single person. However, beyond that person, this track loops back onto the main line towards the five, and if it weren't for the presence of that person, who will stop the trolley, flipping the switch would not save the five.
Should you flip the switch?