Question

The radius of a sphere and of a cylinder are the same. The diameter of the sphere and the height of the cylinder are also the same and are twice the length of the radius. If two cones are formed within the cylinder, as shown in the diagram, then the volume of the sphere is equal to which of the following?

(Points : 1)
the volume of the cylinder + 2(volume of one cone)

the volume of the cylinder 2(volume of one cone)

2(volume of one cone)

the volume of one cone

Answer 1

@Mertsj can you help me?

Answer 2

V of sphere = 4/3 pi r^3

Answer 3

Volume of Cylinder = pi r^2(2r)=2pi r^3

Answer 4

Volume of cone = 1/3 pi r^2(r)=1/3 pi r^3

Answer 5

So using those volumes, you can multiply and add the various choices to see which one turns out to be the volume of the sphere.

Answer 6

but how?

Answer 7

the volume of the cylinder + 2(volume of one cone)
That is your first choice.
What is the volume of the cylinder?

Answer 8

6.28?

Answer 9

Did you read my previous posts?

Answer 10

There is one that says :
Volume of cylinder =

Answer 11

i saw it i thought i used that one

Answer 12

The volume of the cylinder is 2 pi r^3
That means 2 times pi times the radius cubed. What did you use for the radius?

Answer 13

1

Answer 14

And where did you get the information that the radius is 1?

Answer 15

So my point is that the radius is NOT given and the Volume of the cylinder is:
\[2\pi r^3\]

Answer 16

oh ok