Results 1 to 7 of 7

Math Help - Help needed...thanks

  1. #1
    Senior Member
    Joined
    Feb 2008
    Posts
    383

    Help needed...thanks

    The capacity of a small cylindrical tank is 40 litres. A large cylindrical tank is twice as tall as the small tank and it's diameter is three times the diameter of the small tank. Calculate the capacity of the large tank. Thanks.
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Like a stone-audioslave ADARSH's Avatar
    Joined
    Aug 2008
    From
    India
    Posts
    726
    Thanks
    2
    Volume of a cylinder is =V=\pi r^2h


    V_1=\pi (r_1)^2(h_1)

    V_2=\pi (r_2)^2(h_2)

    Divide both the equation

    r_2 = 3r_1

    h_2= h_1
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Senior Member
    Joined
    Feb 2008
    Posts
    383
    THanks for you respond!

    So it's pi*3r^2*2h=answer?

    I dont quite get your equation, please explain it further!

    And what would be the answer?
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Like a stone-audioslave ADARSH's Avatar
    Joined
    Aug 2008
    From
    India
    Posts
    726
    Thanks
    2
    Quote Originally Posted by BabyMilo View Post
    pi *r^2*h= volume of smaller

    So it's pi*(3r)^2*(2h)=18pi* r^2* h=18 volume of smaller
    .........read quote
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Senior Member
    Joined
    Feb 2008
    Posts
    383
    So you are saying 18 is the volume of the smaller cylindrical tank ?
    but shouldnt it be 40? as 40 litres= 40cm^3

    cant you just tell me the answer?
    Follow Math Help Forum on Facebook and Google+

  6. #6
    Super Member

    Joined
    May 2006
    From
    Lexington, MA (USA)
    Posts
    11,909
    Thanks
    771
    Hello, BabyMilo!

    The capacity of a small cylindrical tank is 40 litres.
    A large cylindrical tank is twice as tall as the small tank
    and it's diameter is three times the diameter of the small tank.
    Calculate the capacity of the large tank.

    Let r = radius of the small tank.
    Let h = height of the small tank.

    The volume of the small tank is: . v \:=\:\pi r^2h\;=\;40 litres.


    The radius of the large tank is: .  R = 3r
    The height of the large tank is: . H = 2h

    The volume of the large tank is: . V \:=\:\pi R^2H \:=\:\pi (3r)^2(2h)

    So we have: . V \;=\;18\underbrace{\pi r^2h }
    . . . . . . . . . ^{\text{This is the volume of the small tank}}

    Therefore: . V \:=\:18(40) \:=\:720 litres.

    Follow Math Help Forum on Facebook and Google+

  7. #7
    Senior Member
    Joined
    Feb 2008
    Posts
    383
    Quote Originally Posted by Soroban View Post
    Hello, BabyMilo!


    Let r = radius of the small tank.
    Let h = height of the small tank.

    The volume of the small tank is: . v \:=\:\pi r^2h\;=\;40 litres.


    The radius of the large tank is: .  R = 3r
    The height of the large tank is: . H = 2h

    The volume of the large tank is: . V \:=\:\pi R^2H \:=\:\pi (3r)^2(2h)

    So we have: . V \;=\;18\underbrace{\pi r^2h }
    . . . . . . . . . ^{\text{This is the volume of the small tank}}

    Therefore: . V \:=\:18(40) \:=\:720 litres.

    Very clear, thanks alot!
    Oh, one last thing, where did u get the 18 from?

    Oh, i see 3^2*2. Thanks the first guy as well!
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. A little bit of help needed please!
    Posted in the Algebra Forum
    Replies: 3
    Last Post: September 4th 2009, 11:19 AM
  2. Help needed please
    Posted in the Algebra Forum
    Replies: 10
    Last Post: January 20th 2009, 08:40 PM
  3. Help needed
    Posted in the Algebra Forum
    Replies: 1
    Last Post: January 20th 2009, 09:04 AM
  4. more help needed
    Posted in the Algebra Forum
    Replies: 1
    Last Post: July 21st 2008, 10:04 AM
  5. Help needed please!
    Posted in the Calculus Forum
    Replies: 10
    Last Post: April 27th 2008, 03:16 PM

Search Tags


/mathhelpforum @mathhelpforum