In a vessel, there are 10 litres of alcohol. An operation is defined as taking out five litres of what is present in the vessel and adding 10 litres of pure water to it. What is the ratio of alcohol to water after two operations?
a) 1 : 5
b) 2 : 3
c) 1 : 6
d) 3 : 2

• answer is a i.e 1:5
  
  here vessel initially contains 10 litres of alcohol and 0 litres of water
  in first operation 5 ltrs of alcohol is taken out and 10 ltrs of water is added.
  so after first operation 5 ltrs of alcohol and 10 ltrs of water are there in the vessel
  in the second operation 5 ltrs are again taken out
  but as now alcohol and water are in the ratio of 1:2
  or alcohol is one third of total quantity and water is two thirds of total quantity
  so amount of alcohol taken = one third of total amount taken
  =5/3 ltrs
  and amount of alcohol taken = two thirds of total amount taken = 10/3 ltrs
  now quantity of alcohol remaining = 5-5/3 ltrs= 10/3 ltrs
  and amount of water remaining = 10-10/3 ltrs = 20/3 ltrs
  
  after that 10 ltrs of water is added
  so amount of water after that = 20/3+10 = 50/3 ltrs
  
  so ratio of alcohol to water = (10/3)/(50/3) = 1:5
  
• 11 years agoHelpfull: Yes(111) No(6)
• Final concentration = Initial concentration (1−replacement quantity/final volume)
  Final concentration = =1×(1−10/15)=13
  Final concentration = 13×(1−10/20)=16
  So ratio of alcohol : water = 1 : 5
• 10 years agoHelpfull: Yes(6) No(14)
• Final concentration = Initial concentration (1−replacement quantity/final volume)
  Final concentration = =1×(1−10/15)=1/3
  Final concentration = 13×(1−10/20)=1/6
  so,after 2 operations concentration is 1/6.hence,final volume should be 6 unit.
  So ratio of alcohol : water = 1 : 5 as (1+5=6)
  
• 9 years agoHelpfull: Yes(5) No(6)
• did anyone got hall ticket..for tcs drive
• 7 years agoHelpfull: Yes(5) No(1)
• it should be 1:5 option a is correct.
• 11 years agoHelpfull: Yes(3) No(7)
• : Final concentration = Initial concentration(1−replacement quantityFinal volume)
  Final concentration = 1×(1−10/15)=13
  Final concentration = 13×(1−10/20)=16
  So ratio of alcohol : water = 1 : 5
  
• 10 years agoHelpfull: Yes(1) No(12)
• priya can u xplain ur answer clearly that how 1:5 ?
• 10 years agoHelpfull: Yes(1) No(3)
• 1:5 is the ratio
• 10 years agoHelpfull: Yes(1) No(1)
• plz anyone send me TCS latest paper to this id-rishikesh0091@gmail.com
  and give some tips to crack interview its urgent tcs coming for us less than 4 days........plz hurry.....
• 11 years agoHelpfull: Yes(0) No(22)
• 3 days remain 4 tcs placement
  plz send any useful link or question to crack exam
  my id is lokesh.fating@rediffmail.com/lokesh.fating@outlook.com
• 11 years agoHelpfull: Yes(0) No(8)
• 3 days remain 4 tcs placement
  plz send any useful link or question to crack exam
  my id is lokesh.fating@rediffmail.com/lokesh.fating@outlook.com
• 11 years agoHelpfull: Yes(0) No(10)
• some 1 pls clear it full confusion?
  
• 10 years agoHelpfull: Yes(0) No(1)
• i think 1:5 is correct ans
• 9 years agoHelpfull: Yes(0) No(1)
• not a week is left for a tcs to come..pls give some imp qs to crack the test
  dipalisoni317@gmail.com
• 9 years agoHelpfull: Yes(0) No(1)
• answer is 1:5
  
• 9 years agoHelpfull: Yes(0) No(0)
• answer is 1 because
  rate of stream=1/2*(rate of downstream-rate of upstream)
  0.5*2=1
• 9 years agoHelpfull: Yes(0) No(4)
• 1:5
  
  
  
• 8 years agoHelpfull: Yes(0) No(0)
• only 3 days left for tcs exam. plz guide me how to study
  amuraghav14@gmail.com
• 7 years agoHelpfull: Yes(0) No(0)