Info on Translations Section
Who decides (or how is it decided) which translation is the final chosen translation for the articles? Are the articles pre-translated and then you have to come up with the one that mostly closely matches the original translated version?
Someone at Duolingo will have to deliver the definitive answer. I'm just offering theories and opinions.
The material is not pre-translated. That would defeat the purpose, since, in the longer term, Duolingo hopes to make money by offering our crowdsourced translation capability to those that need translations. The exact mechanism for choosing the "best" translation is a secret that Duolingo seems happy to keep to themselves (and it's continually changing anyway), but the "best" translation is determined by some computer selection algorithm that takes into account (at the very least) user votes on which translation offered is the best. What other factors come into play are kept a secret.
Over the past few months, the translation interface has changed, and changed again and changed again. Things do appear to be improving, which is great, but the system still frequently picks "best" translations that are crap. I think there are ways this can be improved, and I'm sure more changes are in store for the future. I remain guardedly optimistic.
As usual, I don't know. However, I get the feeling that there is no fixed number of submissions before a "best" is chosen (although there may be a minimum number required). Instead, I think it may also depend on how much the various candidates vary from each other. That is, if it is a simple sentence and every submission is exactly the same, then I think that becomes the final (or "best") translation very quickly. If there is a lot of variability in the responses, then it takes longer for the computer to converge on the "best" solution.
But, like I said, I don't really know. That's just the feeling I get from working with the interface. And even if it does work that way today, it will work some other way a month from now :-)