To complete a task two men work on first day and three men work on second day and so on ,till it gets completed.If the same work can be completed by 9 mens for 15 days,in how many days will the work be completed in earlier case?

• 54 days??
  
• 10 years agoHelpfull: Yes(2) No(1)
• work done by 9 men in 15 days will be 135 units.
  it is said that
  on 1st 2 men will work
  on 2nd day 3 men will work
  similarly on 3rd day 4men will work on so on..
  all the work done by these men is same as 9 men
  i.e
  2*1+3*1+4*1+...n=135
  adding 1 on both sides
  1+2+3+4..n=135
  n*(n+1)/2=135
  n2+n-272=0
  n2+17n-16n-272=0
  n=16
  so work will be completed in 16 days.
• 9 years agoHelpfull: Yes(1) No(0)
• answer 15
  
  2*1+3*1+4*1+...n=135
  adding 1 on both sides
  1+2+3+4..n=136
  n*(n+1)/2=136
  n2+n-272=0
  n2+17n-16n-272=0
  n=16
  as 2 person worked on first day and 16 on last day
  total no. of days is 15.
  
• 8 years agoHelpfull: Yes(1) No(0)
• ans = 15days
  
  since, work of 9 men in 1 day => 9m=1/15
  so, work of 1 man in 1 day => m=1/9*15
  
  ATQ...
  2*(1/9*15) + 3*(1/9*15) + 4*(1/9*15)+....+ upto nth term = 1 {total work}
  => 2 + 3 + 4 +.....+ upto nth term = 9*15
  =>9*15 = n/2 (2*2 + (n-1)*d) {finding out the value of n(total days) by sum of nos. in A.P}
  =>n^2+3n-270=0
  =>(n+18)(n-15)=0
  So, n=15days.
• 8 years agoHelpfull: Yes(1) No(0)
• 18 days will be the answer
• 10 years agoHelpfull: Yes(0) No(1)
• Ans:54
  9M takes 15days
  1M takes 9*15 = 135 days
  takes combination of 2M+3M= 5M= 2 days work
  5M takes 135/5 = 27 days ( if 5M works on the same day )
  if they divided into 2 groups no of days = 27*2 = 54
• 8 years agoHelpfull: Yes(0) No(0)
• 9 men=15 days
  so ,1 man=135 days
  or 135 man=1 day
  2+3+4+5+.....=135
  n/2{2*2+(n-1)*1}=135
  n^2+3n-270=0
  n^+18n-15n-270=0
  n=15
  Ans=15
• 8 years agoHelpfull: Yes(0) No(0)
• 9*15 = 135 DAYS.
  2M+3M = 5M
  135/5 = 27 DAYS.
  
  M1*D1 = M2*D2
  5*27 = 9*D
  D = 15 DAYS
• 7 years agoHelpfull: Yes(0) No(0)