A tank is filled in 5hrs by three pipes a b and c the pipe c is twice as fast as b and b is twice as fast as a how much time will pipe a alone take to fill the tank

• 35 hours
  
  Let c take t hours to fill the tank
  Therefore b takes 2t hours (c is twice as fast as b, so time taken by b is double)
  Similarly a takes 4t hours
  
  Given together they fill in 5 hours
  1/t + 1/(2t) + 1/(4t) = 1/5
  7/(4t) = 1/5
  t = 7*5/4 = 35/4 hours
  
  a takes 4t hours = 4*35/4 = 35 hours
  
• 10 years agoHelpfull: Yes(4) No(0)
• a+b+c=5
  b=2a & c=2b=2*2a=4a
  a+2a+4a=7a can fill in 5 hrs
  so a alone can fill the tank in 5*7=35 hrs
  Ans: 35 hrs
• 10 years agoHelpfull: Yes(2) No(0)
• a+b+c=5;
  as per que..b=2a c=2b=2*2a= 4a
  a+2a+4a=5 so 7a=5 a=5/7
  now b= 2a=2*5/7 = 10/7 c=4a= 4*5/7 =20/7;
  ans a=5/7 b=10/7 c=20/7
• 10 years agoHelpfull: Yes(1) No(0)
• a+b+c's 1 hr work = 1/5
  
  c is twice as fast as b
  so time taken c=b/2 ==> b=2c
  Similarly b=a/2 ==> a=2b ==> a=4c
  Ratio of time taken by a:b:c is 4c:2c:c
  
  So a alone ll fill d tank in 5 * 4/(4+2+1) = 20/7
  
  Ans : 20/7 hrs
  
• 10 years agoHelpfull: Yes(1) No(1)
• given c=2b
  b=2a
  Therefore,c=4a
  and given a+b+c=1/5
  a + 2a + 4a=1/5
  7a=1/5
  a=1/35
  so,a can complte work in 35 days...
  
• 10 years agoHelpfull: Yes(0) No(0)