Father is 5 times faster than son. Father completes a work in 40 days before son. If both of them work together, when will the work get complete?

• ans 50/6
  let son does the work in x days,then father in x/5 days
  x/5=x-40
  x=50
  1/50+1/10=50/6
• 11 years agoHelpfull: Yes(21) No(0)
• Ans-25/3 days
  Explanation-Efficiency is inversely related to time.Let "x" be efficiency of son then that of father will be "5x".
  5x-x=40
  x=10
  total 1 day work is 1/50+1/10=6/50
  hence total time = 50/6
  
• 11 years agoHelpfull: Yes(11) No(0)
• son in d days then father in d/5 days
  d-d/5=40 so d=50days
  so father can do in 10days
  son can do in 50 days so both can in 50*10/50+10=8.33days
• 11 years agoHelpfull: Yes(3) No(0)
• F=5S
  F-S=1/40,
  5S-S=1/40 => S=1/160,
  F-F/5=1/40 => F=1/32,
  SO, F+S = 1/160 +1/32 =>6/160 i,e.
  F+S = 160/6= 80/3=26.66
• 11 years agoHelpfull: Yes(1) No(5)
• this is correct
  As efficiency is inversely proportional to days, If Father : son's efficiency is 5 : 1, then Days taken by them should be 1 : 5. Assume, the days taken by them are k, 5k.
  Given that father takes 40 days less. So 5k - k = 40 ⇒ k = 10
  Father takes 10 days to complete the work. Total work is 10 x 5 = 50 units.
  If both of them work together, they complete 5 + 1 units a day. 6/day. To complete 50 units, they take 50/6 = 8 1/3 days.
• 10 years agoHelpfull: Yes(1) No(0)
• @ tcs target 2014 : is ur ans correct??? i also got the same one.
• 11 years agoHelpfull: Yes(0) No(3)