Question

A ball has a diameter of 9 in. It consists of 2 parts. The inside is a spherical core with a diameter of 6 in. Surrounding the core is a layer of polyurethane.

What is the volume of the polyurethane?
Use 3.14 to approximate pi and express your answer in hundredths.

Answer 1

you will have to find the difference of the volume of the whole ball minus the volume of just the core
to find the outer layer volume

Answer 2

use the sphere volume twice

Answer 3

oh ok

Answer 4

try this one
and put your answer here
if it isn't what I have we will go over this slowly like the last

Answer 5

radius 6 i got 113.04

Answer 6

i mean diameter 6

Answer 7

wait

Answer 8

radius is not 6

Answer 9

diameter is 9
radius is 9/2

Answer 10

i know it is 3

Answer 11

well for the core 3 is right for the radius

Answer 12

i got for diameter 9 the radius 4.5 and got the volume of 381.51cm

Answer 13

@freckles are you there

Answer 14

so what do i do now

Answer 15

omg i keep writting 2 instead of 3

Answer 16

its alright

Answer 17

i dont get the last part in the bottom

Answer 18

you still need to find the volume of the smaller ball inside the big ball

Answer 19

do i subtract the bigger number from the smaller number

Answer 20

the smaller from the bigger

Answer 21

doing the opposite will give you a negative number

Answer 22

oh ok so 113.04 - 381.51

Answer 23

no take the smaller from the bigger lol
\[\frac{4}{3} \cdot 3.14 \cdot (\frac{9}{2})^3-\frac{4}{3} \cdot 3.14 \cdot (\frac{6}{2})^3\\ 381.51-\frac{4}{3} \cdot 3.14 \cdot (\frac{6}{2})^3 \\ 381.51 -113.04\]

Answer 24

sorry i meant the other way around

Answer 25

268.47cm is what i got

Answer 26

great job
except the units part
cm^3 :)

Answer 27

ok one more please

Answer 28

one more will have to wait after i run a quick errand

Answer 29

it will be kinda quick

Answer 30

ok then thank you for your help anyway

Answer 31

i'm back

Answer 32

ok do i start a new one or right here

Answer 33

I don't care
one last question right?

Answer 34

if it is one question I will work on it with you

Answer 35

ya last question

Answer 36

A can of spaghetti has a diameter of 12 cm and a height of 16 cm. The can contains spherical meatballs, each with a radius of 3 cm, that take up 25% of the volume.

How many meatballs are in the can?
Use 3.14 to approximate pi and express your answer as a whole number.

Answer 37

now i'm hungry

Answer 38

oh ok

Answer 39

lol

Answer 40

the spaghetti made me hungry :p

Answer 41

anyways

Answer 42

ok let's go ahead and find the volume of the can

Answer 43

its a sphere volume right

Answer 44

well a can is a cyclinder

Answer 45

oh ya my bad

Answer 46

we will use sphere formula for the meatballs though

Answer 47

ok

Answer 48

i got 1809.56

Answer 49

one sec checking

Answer 50

what did you do to get that
(it is close to what I have but not exact)

Answer 51

ya what did you get

Answer 52

1808.64

Answer 53

see kinda close

Answer 54

i did it on google

Answer 55

i just put volume of a cylinder and type in the radius and height

Answer 56

oh i see what you did

Answer 57

you put pi instead of 3.14

Answer 58

and it wants us to use 3.14 instead of pi
but in reality your answer is more closer than mine

Answer 59

but we should do what the instructions want

Answer 60

ok so your right. right

Answer 61

1808.64

Answer 62

yah

Answer 63

ok so what now

Answer 64

now try to find the volume of a single meatball :)

Answer 65

what formula do i use

Answer 66

they describe meatballs as if they were spheres
so you used the formula for volume of a sphere

Answer 67

so it is 113.1

Answer 68

113.04 is what I have

Answer 69

what so whos right

Answer 70

so pretend there are n meatballs
so the volume that the meatballs make up is
n*113.04
and we are given that n*113.04 is .25 of the volume we found from the cylinder
that is:
\[n \cdot 113.05=.25 \cdot 1808.64\]
now we solve for n

Answer 71

\[n \cdot 113.04=.25 \cdot 1808.64\]*

Answer 72

well I did 4/3*3.14*3^3

Answer 73

what did you do?

Answer 74

same thing. on the step you told me to do i dont get it

Answer 75

the equation involving solve for n?

Answer 76

we are given that a number of meatballs is 25% of the can's volume

Answer 77

I just translated that into a mathematical equation

Answer 78

i called the number n
n*volume of meatball=.25*volume of can

Answer 79

divide both sides by volume of meatball
to solve for n

Answer 80

so whats the equation again

Answer 81

\[n=\frac{.25 \cdot 1808.64}{113.04}\]

Answer 82

i got 4

Answer 83

sounds great

Answer 84

that sounds like a horrible spaghetti an
because I prefer a lot of meatballs

Answer 85

Thank you for all your help.

Answer 86

can*

Answer 87

the answer is 4 right

Answer 88

yes that is what we came up with
there are 4 meatballs

Answer 89

hello