A and B worked on a job for 4 hrs and finished half of it. A worked thrice as fast as B did. If B then left A and was joined by C and they finished the job in 1 hour , how long it would have taken for C to do the whole job alone?

• A:32/13 2.46Days
  (1/A+1/B)4=1/2
  and :: 1/A=3/B
  So, 1/A=1/32;
  (1/A+1/C)*1=1/2
  So, 1/C=13/32
  C=32/13 or 2.46days
• 10 years agoHelpfull: Yes(30) No(13)
• (1/A+1/B)4=1/2
  and :: 1/A=3/B
  So, 1/A=1/32;
  (1/A+1/C)*1=1/2
  So, 1/C=1/2-1/32=16-1/32=15/32
  C=32/15
  
  
• 10 years agoHelpfull: Yes(24) No(7)
• @rahul
  
  IF 1/A=3/B
  then 1/B=1/3A
  
  so(1/A+1/B)4=1/2
  (1/A+1/3A)=1/8
  1/A=3/32
• 10 years agoHelpfull: Yes(13) No(3)
• sorry to say but you all are wrong
  solution is= (1/A+1/B)=1/2*4
  1/A=3/B
  ::1/A=3/32
  (1/A+1/C)*1=1/2
  HENCE C WILLDO IT IN 32/13=2.46 HRS
  
• 10 years agoHelpfull: Yes(9) No(0)
• If B then left A and was joined by C
  
  What does it means. any one explain me please.
  Thanks in advance
  
• 10 years agoHelpfull: Yes(8) No(0)
• First Let that total work is 8 Units.
  
  Given that A & B complete half of the work in 4 Hr.
  
  i.e in 4 hr they complete 4 Unit of work. (Simple............ 8 Unit/2)
  
  that mean remaining work is 4 Units.
  
  Also it is given that A and C complete that remaining work in 1 Hr.
  
  So,
  
  A and B together-- 4 Hr. -> 4 Unit
  
  in 1 Hr. they will complete 1 Unit
  
  Now divide this 1 Unit in two parts such that A is 3 times of B
  
  Which is Simple for A- 3/4 and for B- 1/4
  
  A ------- 1 hr. work is 3/4 unit.
  B -------- 1 Hr. work is 1/4 unit.
  -------------------------------------------------
  A and B 1 Hr. work is 1 Unit
  
  Same for And C
  
  A and C together-- 1 Hr. -> 4 Unit
  
  A ------- 1 hr. work is 3/4 unit.
  C -------- 1 Hr. work is x Unit
  -------------------------------------------------
  A and C 1 Hr. work is 4 Unit
  
  Hence the only value for C is 13/4 Units ( 3/4 + x = 4)
  
  Hence 1 Hr work for C is 13/4 Units --------- 13/4 Unit/hour
  
  Total Work Is 8 Unit
  
  Total Work is (8 Unit) / 13/4 = ( 8 * 4)/ 13 === 2.46 hours.........
  
• 9 years agoHelpfull: Yes(7) No(1)
• c alone can do it in 2.13 hrs
• 10 years agoHelpfull: Yes(3) No(0)
• Youa all are missing unit its in hrs 4(1/a+ 1/b)=1/2 also 1/a= 3/b therefore a=1/32 unit wrk in 1 hr
  Nw 1/a+1/c=1/2 putng a we get c
• 10 years agoHelpfull: Yes(3) No(1)
• 4 hrs =50% of the work
  8 hrs =100%of the work
  final equation
  1/3t+1/t=1/8
  t=32/3
  t=A=10.75% of the work do
  now b go out and A and C do rest of work
  remaining work 50%
  A completes 10% and remaining 40% completes by C
  therefore 1 day work is 100/40= 2.5(approximately)
• 10 years agoHelpfull: Yes(2) No(1)
• @avinash question is how long it would have taken for "C" to do the whole job alone? not A
  
• 10 years agoHelpfull: Yes(1) No(1)
• Ans:32/15
  
  
  
  
  
• 9 years agoHelpfull: Yes(1) No(0)
• 100% sure right answer.
  explanation
  
  A+B=4HRS=1/2 WORK
  
  A+B=8HRS=1 (FULL WORK )
  1/A = 3/B
  A+B=8HRS
  1/(B/3) +1/B = 1/8
  B = 32
  1/A = 3/B
  1/A = 3/32
  
  (3/32 +1/X ) = 1/2 WORK
  SOLVING THIS
  WE GET
  X = 32/13 HRS ( i.e C )
  
  
• 8 years agoHelpfull: Yes(1) No(0)
• 2 hours 8 mins am i correct
• 10 years agoHelpfull: Yes(0) No(0)
• (A+B) work in 4 hrs=1/4
  (A+B)=1/4*2
  A=3B so B=1/8 and A=3/8
  Remainin work done by A+c=1/2
  C's work=1/8 so c alone can do it in 8hrs
• 10 years agoHelpfull: Yes(0) No(3)