The first team to have the highest percentage of [its team members] [complete a task] WINS!Since the judging is based on the highest percentage of team members completing a task, it would seem that the percentages would have to be computed once the contest time period is over. Then a comparison between the various percentages can be made. In order to do that, there must be a cut-off time at which point the percentages are calculated. However, there is no cut-off time -- this contest is over when the first team obtains the highest percentage of members completing the task. That's too many variables -- you need to either fix the percentage that constitutes a win, or fix the end time.
I suppose that these rules can be objectively interpreted as meaning that the first team to reach 100% completion wins. However, I doubt any team will have 100% completion.
I really should join dot_pedantic for this sort of stuff.