Q:
      
      
         
            
A can complete a work in 12 days with a working of 8 hours per day. B can complete the same work in 8 days when working 10 hours a day. If A and B work together, working 8 hours a day, the work can be completed in --- days  ?
         
       
      
      
      
          
      
      
          Answer & Explanation
         Answer: D) 60/11          
         
Explanation: A can complete the work in 12 days working 8 hours a day
=> Number of hours A can complete the work = 12×8 = 96 hours 
=> Work done by A in 1 hour = 1/96
 
B can complete the work in 8 days working 10 hours a day
=> Number of hours B can complete the work = 8×10 = 80 hours 
=> Work done by B in 1 hour = 1/80
 
Work done by A and B in 1 hour = 1/96 + 1/80 = 11/480
 => A and B can complete the work in 480/11 hours
 
A and B works 8 hours a day.
Hence total days to complete the work with A and B working together 
= (480/11)/ (8) = 60/11 days
       
      
      
      
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