No, that complicates the situation. I wouldn't kill anybody actively other than in self defense.
The first situation is relatively simple so you can give a short answer based on math.
But most real situations aren't that simple, so you know something about what happened before and who are the people and else.

I believe most people would apply math if they are forced to give a quick answer on the street. But they are totally disconnected from the situation. This being easily exploitable by warmongers makes it a good choice as propaganda material.

@ysss: A slight variation. There is a blackbox with 6 people in it. And it has a knob that let's you choose how many people it kills. It has two settings, 1 and 6 and it's set to 6. Do you change it to 1?