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Math Help - Urgent Measurement Question

  1. #1
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    Urgent Measurement Question

    ..
    Last edited by ~NeonFire372~; June 5th 2008 at 05:30 AM.
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  2. #2
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    well for no. 1 you will need to use the formula for the volume of a sphere
    which is
    V= 4/3r^3 (someting like that) sub the values in and solve for r
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  3. #3
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    Could anyone else provide more detailed answer?
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  4. #4
    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by ~NeonFire372~ View Post
    I have a few questions:

    1. How do I calculate the radius of the sphere with a volume of 45.7 metres^3.?
    for a sphere, the volume is given by

    V = \frac 43 \pi r^3

    where r is the radius. you are given V, so we have:

    45.7 = \frac 43 \pi r^3

    just solve for r

    2. How can I find the height of this? A cone-shaped unit holds 5000 cubic metres (m^3). The radius is 15 metres.
    The volume of a cone is given by:

    V = \frac 13 \pi r^2 h

    where r is the radius and h is the height.

    you are given V and r, so we have:

    5000 = \frac 13 \pi (15)^2 h

    just solve for h

    3. How do I calculate the surface area and volume of the following spheres:

    a) The sphere has a radius of 10cm.
    b) The sphere has a radius of 5cm.
    c) The sphere has a radius of 15.2cm.
    d) The sphere has a radius of 20cm.
    The surface area for a sphere is given by:

    S = 4 \pi r^2

    where r is the radius. just plug in the value of r for each and solve for S

    do the same for the volume. i gave you the formula earlier
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  5. #5
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    Quote Originally Posted by Jhevon View Post
    for a sphere, the volume is given by

    V = \frac 43 \pi r^3

    where r is the radius. you are given V, so we have:

    45.7 = \frac 43 \pi r^3

    just solve for r

    The volume of a cone is given by:

    V = \frac 13 \pi r^2 h

    where r is the radius and h is the height.

    you are given V and r, so we have:

    5000 = \frac 13 \pi (15)^2 h

    just solve for h

    The surface area for a sphere is given by:

    S = 4 \pi r^2

    where r is the radius. just plug in the value of r for each and solve for S

    do the same for the volume. i gave you the formula earlier
    I get most of it but can you explain exactly how I 'solve for h' in the height one?
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