4. It is 12:00 and people are lining up for the matinee at the Bijou Cinema Six. In the first five minutes (12:05), 6 people get into line. At the end of the second five minutes (12:10), there are 11 people in line. At the end of the third five minutes (12:15) there are 16 people in line. If the people keep lining up at this rate, what time will it be when there are 81 people in line?



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