It takes 4 workers a total of 8 hours to build a giant machine with each worker working at the same rate. If four workers start to build the machine at 11:00 AM, and one extra worker per hour is added beginning at 3:00 PM, at what time will the machine be complete?  Choose the correct choice from the following:
A) 5:43  B) 5:56  C) 6:09  D) 6:22  E) 6:35
4 workers build 1/8 of a machine in one hour.   1 worker builds 1/32 of a machine in one hour.   In the first 4 hours, 4 workers build 4*(1/32)*4=16/32 of a machine   From 3:00 to 4:00, 5 workers build another 5/32. The total is 21/32.   From 4:00 to 5:00, 6 workers build another 6/32. The total is 27/32.   To build another 5/32, 7 workers need (5/7)*60 minutes which is about 43 minutes.   The machine is complete at about 5:43.   The answer is 5:43.
<result>A</result>
It takes 4 workers a total of 8 hours to build a giant machine with each worker working at the same rate. If four workers start to build the machine at 11:00 AM, and one extra worker per hour is added beginning at 3:00 PM, at what time will the machine be complete?