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I'm not good with volume. Please help!

 Nov 12, 2018
 #1
avatar+107405 
+1

First one :

 

Volume of a cylinder  =  pi * radius^2 * height

 

Radius of top cylinder  = 24/2  = 12

Height of top cylinder = 60 - 40  = 20

 

Radius of bottom cylinder  = 30/2  =  15

Height of bottom cylinder =  40

 

So....total volume  is

 

pi  [ 12^2 * 20  + 15^2 * 40 ]  =

 

pi [ 144 * 20  + 225 * 40 ]  =

 

pi  [ 2880  + 9000 ]  =

 

pi [ 11880 ]  = 

 

11880 pi  in^3

 

 

cool cool cool

 Nov 12, 2018
 #2
avatar+107405 
+1

Second one

 

Note that the height of the cylinder  =  2 * radius of the sphere

 

And the radius of the sphere  =   radius of cylinder

 

We need to find the radius of the  cylinder

 

432 pi  =  pi *  radius^2  * height

 

432 pi  = pi  * ( radius^2) *( 2* radius)      [ divide out 2, pi ]

 

216  =  radius^3      take the cube root of both sides

 

6  = radius

 

So....the volume of the sphere is

 

(4/3) pi * (radius)^3  =

 

pi *  (4/3) * 6*3

 

pi * (4/3) * 216  =

 

288pi  in^3

 

 

cool cool cool

 Nov 12, 2018
 #3
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+1

Thank you!smiley

Guest Nov 12, 2018
 #4
avatar+107405 
0

No prob   !!!

 

 

cool cool cool

CPhill  Nov 12, 2018

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