As to the scenario, if the one is someone I know and/or feel some connection with, the six strangers are out of luck.
That isn't the point of the exercise. I think its more of an issue of how distant one is from the consequences of the decision. Its much easier to pull a lever to switch the tracks than it is to personally shove a fatass onto the tracks ( I know, people have tried to push me before... not on to tracks, just in general
The reason that I bring all of this up is a quasi-relation to the essay 'The Necessity of Evil' (Anton LaVey, The Devil's Notebook) with respect to positive change as a result of a possibly 'evil' action. Maybe the relation is a bit strained, however.
If one refuses to purposefully kill one person ( a generally 'evil' act ), it results in the death of six. The scenario is supposed to be taken in the idea that nothing is known about any of the subjects. Even following LaVey's idea that no man is equal to the next, its simple statistics that six is better than the one (In that you have 6 chances for excellence instead of 1).