A and B working separately can do a piece of work in 6 and 9 days respectively; they work on alternate days starting with A on the first day. In how many days will the work be done?

• A=1/6 days
  B=1/9 days
  with a starting the work
  in a period of 2 days work done by a and b=1/6+1/9=5/18
  in 3 such perios work done =5/18+5/18+5/18=15/18
  remaining work=1-15/18=1/6
  now its a turns and it can complete the remaining work
  so number of days=3*2+1=7
• 12 years agoHelpfull: Yes(22) No(10)
• 1/6+1/9+1/6+1/9+.......
  5/18+5/18+5/18.....
  15/18+1/6=1
  =7 Days
• 10 years agoHelpfull: Yes(5) No(4)
• For 2 Days: 1/6+1/9=5/18
  for 4 Days: 10/18
  for 6Days:15/18
  7days:15/18 + 1/6 =18/18 =1.
  so,in 7 Days the work will be completed...
• 10 years agoHelpfull: Yes(5) No(4)
• 1/6+1/9+1/6+1/9+.......
  5/18+5/18+5/18.....
  15/18+1/6=1
  =7 Days
• 10 years agoHelpfull: Yes(4) No(2)
• very simple find total work and separate work just make a think you will get the answer as 7 days
  
• 10 years agoHelpfull: Yes(1) No(2)
• (A + B)'s 2 day's work = [1/9+1/12]=7/36
  Evidently, the work done by A and B during 5 pairs of days = [5×7/36]=35/36
  Remaining work = [1−35/36]=1/36
  Now, on 11th day it is A's turn.
  Now 1/9 work is done by A in 1 day.
  1/36 work will be done by A in [9×1/36]=1/4 day
  So, total time taken = 10 1/4 days.
• 9 years agoHelpfull: Yes(1) No(3)
• A can complete total work in 9 days.
  One day work of A = 1/9 part.
  B can complete work in 12 days.
  One day work of B = 1/12 part.
  A and B together can complete work in one day,
  = 1/9 + 1/12
  = (4 +3)/36 = 7/36 part.
  Take, 2 days = 1 time unit.
  To time unit needed to complete the work,
  = 1/(7/36) = 36/7 = 5 time unit approx.
  Total Time = 2 *5 = 10 days.
• 8 years agoHelpfull: Yes(1) No(2)
• 18 days
  Because they work in alternate days.
  Hence calculating.
• 9 years agoHelpfull: Yes(0) No(4)
• the work can be completed in 7 days
  
• 9 years agoHelpfull: Yes(0) No(1)