Thirty men take 20 days to complete a job working 9 hours a day.How many hour a day should 40 men work to complete the job?
(a) 8 hrs
(b) 7 1/2 hrs
(c) 7 hrs
(d) 9 hrs

• 6 3/4 hours
  
  As it is not given, in how many days 40 men have to complete the job, so considering same days(=20) in which 30 men completes the job.
  So If 40 men works for 'x' hours/day for 20 days, then Total men hours=30*20*9 = 40*20*x
  x=(30*20*9)/40*20)= 27/4= 6 3/4
• 8 years agoHelpfull: Yes(7) No(1)
• (30Men x 20days x 9hrs)/(40Men) = 135 hrs per day. Which
  is impossible. So, the answer is none.
  
  Since the question is vague, if you don't answer this
  question you may be given mark for this question.
  
  The question should have been
  
  1. How many days 40 men working 9 hrs a day will take to
  complete the work.
  Answer: (30Men x 20days x 9hrs)/(40Men x 9 hrs) = 15days
  
  2. How many hours a day should 40 men work for 20days will
  take to complete the work.
  Answer: (30hrs x 20day x 9hrs)/(40Men x 20days)=6 3/4 hrs
• 8 years agoHelpfull: Yes(3) No(0)
• 1 mans one day work=1/30*20*9
  30 mans------=1/20*9
  40 mans------=1/40*20*x
  so as man increases no of hours decreases i.e. invers proportion
  
  so 30*9=k
  so 40*h=30*9
  h=30*9/40=27/4:=7 hrs
  
• 8 years agoHelpfull: Yes(1) No(0)