A cistern is filled in 9 hours and it takes 10 hours when there is a leak in its bottom. if the cistern is full, in what time will the leak empty it ?
[A] 15 h
[C] 80 h
[B] 12 h
[D] 90 h

• Ans:90hr
  work done by leak in 1hr=1/9-1/10=1/90
  
• 12 years agoHelpfull: Yes(22) No(0)
• from given data ,in 1 hr part of cistern fill=1/9.
  due to leak,10 hrs require(given data)
  hence,water filled in cistern by inlet-wastage of water by leak = 10 hrs
  let x=water is leaked from bottom
  1/9 -1/x=1/10
  1/x=1/9 -1/10
  1/x =1/90
  x=90
  ANSWER=90 h(d)
  
• 10 years agoHelpfull: Yes(5) No(1)
• a=1/9,
  a+b=1/10,
  b=-1/90
  b=90 hrs.
• 10 years agoHelpfull: Yes(1) No(0)
• [d] 90 hrs
  
• 10 years agoHelpfull: Yes(0) No(0)