SOLUTION: If it takes 3men 56hours to dig a hole 4mX6mX5m, and two of the men work twice as fast as the third,find the number of hours that will take the two faster men to dig this hole

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Question 942153: If it takes 3men 56hours to dig a hole 4mX6mX5m, and two of the men work twice
as fast as the third,find the number of hours that will take the two faster men to dig this hole together. ( answer is 70hours - show your solution )
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +R+ = the rate of working of the slow man
+2R+ = the rate of working of the two faster men
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Add their rates of working to get rate working together
+R+%2B+2R+%2B+2R+=+1%2F56+
+5R+=+1%2F56+
+R+=+1%2F280+
+2R+%2B+2R+=+2%2F280+%2B+2%2F280+
+4R+=+4%2F280+
+4R+=+1%2F70+
It takes 70 hrs for the 2 faster men digging together
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check:
+5R+=+1%2F56+
+5%2A%281%2F280+%29+=+1%2F56+
+1%2F56+=+1%2F56+
OK