A and B working separately can do a piece of work in 20 and 24 days. They work on alternate days starting with B on the first day. In how many days will the work be completed?

• Ans:20+24/2=22days
• 11 years agoHelpfull: Yes(10) No(13)
• They will complete 1/20 + 1/24 = 11/120 work in 2 days
  They together will complete 110/120 work in 20 days
  After 20 days . 10/120 or 1/12 work will be left.
  1/20 work is done by A on 21 st day
  and balance will be done by B on 22nd day.
  
  so total 22 days.
• 12 years agoHelpfull: Yes(9) No(16)
• they will complete 1/24+1/20=11/120 work in 2 days.
  they together can complete 11/12 work in 20 days
  on 21st day B will complete 1/24 work, so now 1/24 work is left
  on 22nd day a will complete the 1/24 work in 5/6 days.
  so, total days = 21 (5/6)days.
• 11 years agoHelpfull: Yes(9) No(2)
• correct answer 21 5/6 days
• 8 years agoHelpfull: Yes(5) No(0)
• The answer would be 22 days.
  Soln : lets divide the piece of work into 600 parts(the lcm of 20 and 24), then in one day A will do 600/20 = 30 parts of work and B will do 600/24 = 25 parts of work. Summing together the parts of works done by A and B, we get that 550 parts will done in 20 days((30 + 25)*10). the rest 50 parts can be done by A and B in 2 days.
• 10 years agoHelpfull: Yes(2) No(1)
• 1 day's of work (A+B)= 1/20 + 1/24=11/120 days
  take 10 pair of days , so .... 10*11/120=11/12 days
  remaining work =1-11/12=1/12 days
  on 21th day if B is starting then =1/12- 1/24=1/24 days
  on 22th day .now A's turn=20*1/24=5/6 days
  so the total no. of days taken by both of them to finish the work = 21(5/6)days
• 8 years agoHelpfull: Yes(2) No(0)
• A+B= 1/20+1/24= 6+5/120=11/120
  means A efficiency 6 units per days and B's efficiency 5 units per day,,,,
  now starting with a B alternate days
  2 days work of A and B is 11 units
  so,20 days work is 110 units
  now its B turn to work on 21st day which is 115 units(B's 5 units per day)
  now on 22nd day its A's turn which is 5/6 units
  so 20+1+5/6= 21 5/6 days
• 8 years agoHelpfull: Yes(1) No(1)
• my answer is 21and4/5days
  Is it there in the option
  ??
• 8 years agoHelpfull: Yes(0) No(2)
• Pls tell correct answer mine is 22 days
• 8 years agoHelpfull: Yes(0) No(2)