Math Question Help please?

Question

I can't remember these can somebody please help me and explain how they came up with the answers.

Find volume of each sphere or hemisphere. Round to the nearest tenth.

1.The Radious of the sphere is 12.4 Centimeters.

4. The Diameter of the sphere is 17 feet.

9. The Circumference of the sphere is 38 meters.

16. The circumference of the hemisphere is 18 millimeters.

Mrs. Gutierrez purchased a cylindrical aquarium for her office. The aquarium has a height of 25 1/2 inches and a radius of 21 inches.

If a cubic foot of water weighs about 62.4 ounds, what is the weight of the water in the aquarium to nearest five pounds.

Answer 1

Ok I will help you get started, cause I don't believe in doing all of people's homework. All these problems are very similar. Ok the first one should be simple using the equation Volume= 4\3 π r^3
just plug in the radius and the answer is in cubic centimeters.

Number 4 is a bit more tricky a diamiter is twice the size of a radius, so take half of the diameter and plug it in

Number nine you need the equation for the circumference of the sphere which is C= 2 π r since you have C solve for r then plug it back into the original volume equation.

Can't help you on 16

The fish tank one you multiply the circumfrence (2 π r) times the height to get volume

On the last one it is simple multiplication, however make sure you convert cubic inches to cubic feet.

Answer 2

volume of sphere : 4/3 * pi r^3
volume of hemisphere : 2/3 * pi r^3
circumference of sphere around its widest part : 2 pi r
circumference of hemisphere around its widest part : 2 pi r
volume of cylinder : h pi r^2
pi = 3.14
diameter = 2 * radius
radius = 1/2 * diameter
1 cu ft = 1728 cuin

1) 4/3 * pi 12.4^3
= 4/3 * 3.14 * 12.4 * 12.4 * 12.4
= 7982.4 cucm

4) 17 * 1/2 = 8.5 ft (radius)
4/3 * pi 8.5^3
= 4/3 * 3.14 * 8.5^3
= 4/3 * 3.14 * 8.5 * 8.5 * 8.5
= 2571.1 cuft

9.) 38 m = 2 pi r = 2 * 3.14 * r = 6.28 * r
38/6.28 = r
r = 6.1
volume = 4/3 * pi * 6.1^3
= 4/3 * 3.14 * 6.1 * 6.1 * 6.1
= 950.3 cumeters

16) 18 mm = 2 pi r = 2 * 3.14 * r = 6.28 * r
18/6.28 = r
r = 2.9 mm
volume = 4/3 * pi * 2.9^3
= 4/3 * 3.14 * 2.9 * 2.9 * 2.9
= 102.1 cumm

volume of aquarium:
h * pi * 21^2
h : 25 1/2 = 25.5 in
r : 21 in
h * pi * 21^2 = 25.5 * 3.14 * 21^2 = 25.5 * 3.14 * 21 * 21
= 35310.9 cuin
weight : 35310.9 cuin/1728cuin per cuft * 62.4 lbs per cuft
= 1275 lbs

Answer 3

yea, like I am going to do YOUR homework.

haha.