A can do a work in 60 days. He works for 15 days and later B alone completes the work in 30 days. In what time will they together complete the work?
(a) 24 days
(b) 25 days
(c) 30 days
(d) 32 days
(e) None of these

• let A can do a work in = 1/60 days
  he does 15 days so work done by A in 15 days= (15) * (1/60) = 1/4
  remaining work is = 1- 1/4= 3/4
  B's one day work is =1/30
  so 3/4 work is done by B in=(3/4) * (1/30) = 1/40 days
  time require to complete the work is= 1/60 + 1/40 = 5/120
  5/120 = 1/24
  so 24 days require to complete the work together.
  
• 7 years agoHelpfull: Yes(29) No(3)
• (a) 24 days
  
  Let working alone, B takes b days to complete the work, then
  A's 15 days work+ B's 30 days work = 1
  (15/60) + (30/b) = 1
  => 30/b=1 - (1/4)
  => b=40
  So working together A and B's 1 day work= (1/60)+(1/40)=5/120=1/24
  Hence they will take 24 days to complete the work.
• 7 years agoHelpfull: Yes(7) No(1)
• Total unit work=60
  A completed work in 60 days---1 u/d
  A's 15 day's work=15unit
  Remaining unit(u)=60-15=45unit
  B completed 45 unit in 30days i.e 45/30=3/2unit/day
  hence A+B =1+3/2=5/2unit/day
  total unit=(60*2)/5=24 days
• 7 years agoHelpfull: Yes(5) No(0)
• solution is:-
  A 1 day's work= 1/60
  A 15 days' work= 15*(1/60)=1/4 work
  hence, remaining work= 1-(1/4)=3/4
  now, remaining 3/4 work is done by B alone.
  so, B did 3/4 work in 30 days. so,
  30 days=3/4 work
  1 day= (3/4) * (1/30)=1/40 work
  hence, (A's + B's) 1 day work together= 1/60 + 1/40=5/120=1/24
  so,
  1 day=1/24 work
  24 days= 1 work
  therefore, answer is 24 days.
• 6 years agoHelpfull: Yes(3) No(0)
• 24 is the answer
  
• 7 years agoHelpfull: Yes(1) No(0)
• A 1 day work=1/60, therefore, 15 days work=1/4
  work left=1-1/4=3/4
  3/4 work is completed by B in 30 days. Therefore, B will take 40 days to complete whole work.
  Now, 1/60+1/40=5/120=1/24
  Hence, 24 days.
• 7 years agoHelpfull: Yes(1) No(0)
• Answer is 24 days
• 7 years agoHelpfull: Yes(0) No(1)
• Answer 24 days
• 7 years agoHelpfull: Yes(0) No(1)
• TOTAL WORK =60UNIT
  A IN 1 DAY=1UNIT
  A IN 15 DAY =15UNIT,B IN 30 DAY=60-15=45UNIT
  BIN 1DAY=1.5UNIT
  BOTH 1 DAY =2.5UNIT
  BOTH CAN COMPLETE WORK IN=60/2.5=24DAY
• 6 years agoHelpfull: Yes(0) No(0)
• A=1/60 Now A worked 15 days so
  A 's 1 day work = 15*1/60 =1/4
  then B's remaining work 1-1/4=3/4
  For B = 3/4*1/30 = 40
  then A = 1/60 B= 1/40
  then completed by them will be 1/60+1/40=100/60*40= 24days ANS
• 6 years agoHelpfull: Yes(0) No(0)
• A's work per day=1/60
  A's work for 15 days+B's work for 30days=1
  15*(1/60)+30(x)=1
  x=1/40
  A and B together can complete work in 1 day
  (1/60)+(1/40)=1/24
  total time to taken will be 24 days;
• 5 years agoHelpfull: Yes(0) No(0)