Help me find the volume....?

Question

Answer the ones you can

1) Density= mass/volume
mass= .5 gram
volume= 6 liters
find density

2) Find the Volume for the Cone(v= 1/3 • π • r² • height)
height= 15 inches
diameter= 9 inches

3) Find the Volume for the Piramid (v= 1/3bh)
height= 9
base=42

4) Find the Volume for the Cylinder (v= π • r² • height)
volume= 15 inches/liters
diameter= 6

5) Sphere: (v= 4/3 • π • r³)
volume= 36
find the radius

Thank you.

Answer 1

1) Density is usually expressed in g/cm³, but we'll keep it in lilters:

m = 0.5 gm
V = 6l
D = m / V
D = 0.5 / 6
D = 0.0833 gm / l
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2) h = 15in.
d = 9 in.
Find r;
r = d / 2
r = 9 / 2, or 4.5 in.
V = 1/3 π r² h
V = (3.14159 * (4.5)² * 15) / 3
V = (3.14159 * 20.25 * 15) / 3
V = 954.258 / 3
V = 318.086 cu. in.
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3) The volume of a regular pyramid is V = 1/3(Base Area * Height), so your formula is wrong.

h = 9 units
b = 42 units
A = b²
A = 42²
A = 1746 sq. units
V = Ah / 3
V = (1746 * 9) / 3
V = 15714 / 3
V = 5238 cu. units
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4) You ask for the volume, but then you give it, so the problem is misstated.

5) V = 36 cu. units
V = 4/3 π r³, or (4 π r³) / 3
Solve for r:
Multiplying both sides by 3:
3V = 4 π r³
Dividing both sides by 4 π:
3V / 4 π = r³
Taking the cube root of both sides:
³√(3V / 4 π) = r, or
r = ³√(3V / 4 π)
r = ³√((3 * 36) / (4 * 3.14159))
r = ³√(108 / 12.5664)
r = ³√8.5943
r = 2.0483 units
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Answer 2

All you need is a calculator and a piece of paper and a pencil. There is no reason you can't solve these equations. All you do is plug in the numbers in the right place and solve for the missing variable using basic operations.

I will give you one hint. Pi = 3.14. Though most calculators have a pi button.