Three pipes a b and c can fill a tank in 6hrs. after working at it together for 2 hrs c is closed and a and b can fill the remaining part in 7hrs. The number of hours taken by c alone to fill the tank is

• 14 hours
  
  Let a and be take x hours to fill the tank
  and c take y hours to fill the tank
  
  Together they can fill in 6 hours
  1/x + 1/y = 1/6 ---(1)
  
  ===> in 1 hour = 1/6 is filled
  in 2 hours = 1/6*2 = 1/3 filled
  
  Remaining fraction to be filled = 2/3
  
  a and b takes 7 hours to fill 2/3 part
  7 hours --- 2/3 part
  x hours ---- 1 part
  
  x = 7*3/2 = 21/2 hours
  
  put x =21/2 in equation (1)
  
  2/21 + 1/y = 1/6
  1/y = 1/14
  ===> y= 14 hours
  
  c alone takes 14 hours to fill the tank
• 10 years agoHelpfull: Yes(7) No(0)
• sorry its 14 hrs
  
  
• 10 years agoHelpfull: Yes(3) No(0)
• a + b + c's 1 hr work = 1/6
  a+b + c 's 2 hr work = 2 * 1/6 = 1/3
  
  Remaining work = 1 - 1/3 = 2/3
  
  a+b ll fill 2/3 part of tank in 7 hrs
  a+b ll fill d full tank in 3/2 * 7 = 21/2
  
  Part of d tank filled by c in 1 hr = (a+b+c)'s 1hr work - (a+b)'s 1 hr work
  ===> 1/6 - 2/21 = 9/126 = 3/42 = 1/14
  
  C ll fill d full tank in 42hrs
  
  Ans : 42hrs
  
• 10 years agoHelpfull: Yes(1) No(3)
• a+b+c do in 1hr=1/6..........................................(i)
  a+b+c do in 2hrs=1/6*2=1/3
  Remaining=1-1/3=2/3
  
  a+b do 2/3 part in 7 hrs.
  a+b do 1 part full in 21/2 hrs.
  
  a+b do in 1hr= 2/21.........................................(ii)
  
  By doing, (i)-(ii), we get-
  
  c=1/14.
  So, c does the full work alone in 14hrs.
• 10 years agoHelpfull: Yes(1) No(0)
• a + b + c=1/6
  for 2hrs work completed is 2(a+b+c)=2(1/6)=1/3
  so, work remaining=1-1/3=2/3
  2/3work done by a+b in7hrs..
  whole work by a+b=2/3*7= 2/21
  therefore,(a+b+c) - (a+b) =1/6 - 2/21 = 1/14
  so, c takes 14 days to complete whole work...
  
• 9 years agoHelpfull: Yes(1) No(1)
• A+b+c=6hr; means 100/6=16.66% of work in in hr
  So 2hr work is 2×16.66=33.32%
  Remaining work is 66.68%
  A+b fill the remaining part 66.68/7=9.52%
  So 1 hr work of c=(a+b+c)-(a+b).......1hr work
  I.e approx 5.14% and will be 100/5.14 ...
  So approx near to 19hr ....
• 10 years agoHelpfull: Yes(0) No(0)
• 4.5
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• 10 years agoHelpfull: Yes(0) No(3)