. Pipe A takes 16 min to fill a tank. Pipes B and C, whose cross-sectional circumferences are in the ratio 2:3, fill another tank twice as big as the first. If A has a cross-sectional circumference that is one-third of C, how long will it take for B and C to fill the second tank? (Assume the rate at which water flows through a unit cross-sectional area is same for all the three pipes.)

• If A has a cross-sectional circumference that is one-third of C,and Pipes B and C, have cross-sectional circumferences area in the ratio 2:3, then cross-sectional circumferences area of A:B:C is in the ratio 1: 2:3.
  
  Then when a single unit is filled by pipe A, 5 units are filled by B and C in same time.
  Then time taken by B and C to fill second tank of double volume will be 2*16/5= 32/5 mins or 6 mins 24 secs.
• 13 years agoHelpfull: Yes(29) No(32)
• If A has a cross-sectional circumference that is one-third of C,and Pipes B and C, have cross-sectional circumferences area in the ratio 2:3, then cross-sectional circumferences area of A:B:C is in the ratio 1: 2:3
  If pipe A can fill a container in 16 min. then
  the volume filled during 16 min. is =pie*r^2( due to having circular mouth of pipe it will give out circular area through out time i.e 16min.)
  
  therefore we can say that:
  volume of container A is=16*pie*r^2
  r=1(radius of pipe A)
  therefore VOL. of =16*pie*1=16*pie
  Given: second container is twice of first therefore
  vol. of second container is=2*16*pi=32*pie
  
  32*pie=t*(pie*Rb+pie*Rc)
  where :
  t=time taken by B and C to fill container(which we have to find)
  Rb=crosection radius of pipe B i.e=2
  Rc= crosection radius of pipe C i.e=3
  
  32*pie=t*(pie*2*2+pie*3*3)
  32*pie=t*pie(4+9)--->taking pie common and squaring the rad. value
  32=t(13)--> cancling pie value
  32/13= t
  therefor time taken by B and C to fill container second is 32/13
  
  
• 8 years agoHelpfull: Yes(4) No(0)
• cross-sectional circumference of A=x, B=2x, C=3x
  Area of A=x^2 , B= 4x^2 , C= (3x*3x)=9x^2
  (B+C)= 13x^2
  we know, volumn=speed*time
  for first tank, V=x^2 * 16
  for 2nd tank, 2V=13x^2 * Time
  T=2V/ (13x^2)
  T= 2*x^2*16 / 13x^2
  T=32/13
• 6 years agoHelpfull: Yes(1) No(1)