It takes 6 beavers 10 hours to build a certain dam, working at a uniform rate. If three beavers start to build the same dam at 8:00 AM, and one beaver per hour is added beginning at 6:00 PM, at what time will the dam be complete?	Choices:  A) 7:30 PM  B) 8:00 PM  C) 9:00 PM  D) 10:00 PM  E) 11:00 PM
The rate of 1 beaver is 1/60.   The amount of work done by 3 beavers in 10 hours is 3/60 *10 = 30/60   In the next hour, 4 beavers do 4/60 for a total of 34/60.   In the next hour, 5 beavers do 5/60 for a total of 39/60.   In the next hour, 6 beavers do 6/60 for a total of 45/60.   In the next hour, 7 beavers do 7/60 for a total of 52/60.   In the next hour, 8 beavers do 8/60 for a total of 60/60.   The dam will be completed at 11:00 pm.   The answer is 11:00 PM.
<result>E</result>
It takes 6 beavers 10 hours to build a certain dam, working at a uniform rate. If three beavers start to build the same dam at 8:00 AM, and one beaver per hour is added beginning at 6:00 PM, at what time will the dam be complete?