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

• 6.75 hours
  If number of (days=20) remains same
  hours/day for 40 men to complete the job= (30*20*9)/(40*20)=27/4= 6 3/4 =6.75
• 10 years agoHelpfull: Yes(19) No(1)
• let 40 men take x hours .
  so according to time work hour equation
  (men)(day)(hour) of 1st = (men)(day)(hour) of 2nd
  so x = (30 *20*9) / (40)(20)
  x = 6.75
  
• 10 years agoHelpfull: Yes(9) No(2)
• 30 men takes 20 days then 40 men will take 15 days to complt the wrk nwo
  30*20*9=40*15*x(hours) after solving x=9 hrs
  ans=9hrs
• 10 years agoHelpfull: Yes(8) No(13)
• one men in one hour = (1/20)*(1/9)*(1/30)
  so 40 men can do work in one hour = 1/(15*9)
  let they do x hours a day and work should be completed in 20 days = (x*20)/(15*9)=1
  so x= (15*9)/20=27/4 is approx to 8 hrs
• 10 years agoHelpfull: Yes(5) No(10)
• 30 man's 1 day work = 1/9 hrs
  1 man's 1 hrs work = 1/(9*30)
  40 man's 1 hrs work = 40/(9*30)
  = 4/27
  total hour in a day the work shd complete = 27/4 = 6.75
• 10 years agoHelpfull: Yes(3) No(1)
• The question it self having the answer. "how many hour a day should 40men work to complete the job?". Here they haven't mentioned the number of days. Read the question again, how many hour a day "should" 40men work to complete the job. They should work for 9 hours only, that is why 6.75 is not included in question. (One of the best example of trick questions)
• 4 years agoHelpfull: Yes(2) No(0)
• MD/W=constant
  Applying this formula let no of hours are 'x'a day and works for 'y' days
  Then 30*20*9=x*y*40 => xy=135
  since we have to find hours per day, divide by options
  135/8=16.875 (its asking hours a day, but answer is implying day in fraction,so this is not a answer)
  similarly, answer 7 is eliminated.
  its either 7.5 or 9
  
• 10 years agoHelpfull: Yes(1) No(9)
• 30 MEN-9HRS A DAY-20 DAYS;I,E 1 MEN 1/270th OF WORK IN 1 DAY.THEN 40 MEN CAN DO WORK IN 40*1/270=6.75
  
• 10 years agoHelpfull: Yes(1) No(1)