Question

Please HELP!!! NEED HELP!!!

Answer 1

What is the question? :)

Answer 2

Hello! I may be able to help :)

Answer 3

what do you need help with

Answer 4

A machine coats metal spheres with a plastic coating. The metal spheres have a radius of 9 mm. The spheres formed by the metal and plastic coating have a radius of 12 mm.

How much plastic coating is on each sphere?
Use 3.14 to approximate pi and express your final answer in hundredths.

[ ? ] mm^3

Answer 5

@DIDITHEDAD @YesThisIsDog @BloomLocke367 @iGreen @mattmatt88 @tylermcmullen23

Answer 6

ok

Answer 7

You need to find the surface area of the metal sphere, which is found by \[4\pi r^2\]

Answer 8

so 4 x 3.14 x 9 ?

Answer 9

almost. 4 x 3.14 x 9^2

Answer 10

^^^

Answer 11

Yeah, I think we use Surface Area.

Answer 12

ok

Answer 13

1017.36

Answer 14

With the plastic coating, the sphere is 12mm, correct?

Answer 15

and then 4 x 3.14 x 12^2

Answer 16

and then subtract?

Answer 17

Yep

Answer 18

791.28?

Answer 19

Correct!

Answer 20

thanks guys!

Answer 21

No problem :)

Answer 22

notice that the answer is supposed to have units of mm^3
That is a hint that you should be finding *volume*

in other words, find
the volume of the coated sphere (use r=12 mm)
then subtract off the volume of the smaller metal sphere (with r=9)

\[ V_{plastic} = \frac{4 \pi}{3} ( 12^3 - 9^3) \]

Answer 23

@phi , running a little late :)

Answer 24

only because the posts up above found surface area, which is not correct