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

• Qn is incomplete.
  
  In this line
  how many hours a day should 40 men work to complete the job?
  
  number of days should be given.
  
  If 15 days, then answer will be 9 hours a day.
  if 18 days, then 7.5 hrs a day.
  
  so pls check.
• 13 years agoHelpfull: Yes(4) No(2)
• 20*30 = 40*x
  x=135. Only 9 from the given options is divisible of 135 . So option D is correct.
• 13 years agoHelpfull: Yes(1) No(1)
• m1*t1*w2=m2*w1*t2
  t2=(30*20*9)/(40*20)=7.5
• 9 years agoHelpfull: Yes(0) No(0)
• Since the no. of days for second instance in not given,considering it as 20
  then total man hours for Instance 1=(30*20*9)=5400hrs
  for instance 2=(40*20*x)=800x
  800x=5400.therefore x=6.25
• 9 years agoHelpfull: Yes(0) No(0)
• *x=6.75hrs
• 9 years agoHelpfull: Yes(0) No(0)
• Taking formula
  m1*d1*t1/w=m2*d2*t2/w
  where m= no of men,
  d =no of days
  t= time
  w= part of work done
  
  30*20*9/1=40*d2*9, keeping 9 hours as constant
  ans comes 15
• 6 years agoHelpfull: Yes(0) No(0)