If one man do a job of two boys. If 12 men’s and 15 boys can do a work in 25 days working 7.5 hrs a day. How many boys are required along with 21 men’s to complete a work twice the first one in 50 days.

• 1 man=2 boys
  so,(12*2+15)boys can do a work in 25 days,working 7.5 hrs a day.
  total amount of work in boy-day-hrs is (39*25*7.5)
  now we have to use just this amnt of work in the question,
  let x boys are required,then we get
  (21*2+x)*50*7.5=2*(39*25*7.5)
  x=-3 ,which is not possible.It means no boy is required .Men are already in surplus mumber.
  note:always use the concept of person-day-hours in such type of problems.Believe me it's very easy and helpful.
• 13 years agoHelpfull: Yes(51) No(2)
• 12 men=24 boys
  so 24+15=39 boys can do it in 25 days..
  now...for 25 days job boys required=39
  for 1 day job boy required=39/25
  for 50 day job boy required=(39/25)*50=78
  already we have 21 men=42 boys...so boys required=78-42=36 boys
• 13 years agoHelpfull: Yes(27) No(23)
• If 12 men and 15 boys can do a work in 25 days working 7.5 hrs a day.
  means
  21 boys can do a work in 25 days working 7.5 hrs a day.
  No. of boys reqd complete a work twice the first one in 50 days = 21*25*2/50 =21boys or 10.5 men .
  
  so no additional boy is reqd as already there are surplus men.
• 13 years agoHelpfull: Yes(9) No(6)
• what about no.of hours working cond time
  
• 10 years agoHelpfull: Yes(0) No(0)
• (21+2x)*50*7.5=2(39*25*7.5)
• 8 years agoHelpfull: Yes(0) No(2)