# Thread: PLz help ! Easy problem , but :S

1. ## PLz help ! Easy problem , but :S

Please help solving this math problem ! It's easy , but ... I'm still a noob. :

Two cylinders A and B have the same shape ( the ratio of the height to diameter is the same for both ) , but cylinder A has twice the volume of cylinder B .
Quests :
a - Show that the ratio of the diameter of A to the diameter of B is

b - Show that the height of cylindre A is roughly 26% greater than the height of cylinder B .

c - Show that the diameter of cylinder B is roughly 79% of the diameter of cylinder A .

d - If the diameter of cylinder B is 151 mm , then find the diameter of A .

Thank u so much in advance !!!

2. erm... I'm not entirely sure on this but I can only do a I think
so A:B
the volume of A is twice as much of the volume of B
so lets put "V" as the volume
so we have:

A:B
2V:V
And volume is a "cubed" measurement (ie. ^3)
and the question is asking for the diameter which is a length measurement (ie. ^1), this means that we have to "cube root" the equations

so we obtain
cube root 2:1
which is cube root of 2 as the answer says
(if you wonder why the V has gone, that's because its a cubed measurement so when it is cube rooted it goes to 1, and cube root 2 x 1 = cube root 2)

PS
I'm not entirely sure of this so don't count it as definate

3. Originally Posted by speed01
Please help solving this math problem ! It's easy , but ... I'm still a noob. :

Two cylinders A and B have the same shape ( the ratio of the height to diameter is the same for both ) , but cylinder A has twice the volume of cylinder B .
Quests :
a - Show that the ratio of the diameter of A to the diameter of B is

b - Show that the height of cylindre A is roughly 26% greater than the height of cylinder B .

c - Show that the diameter of cylinder B is roughly 79% of the diameter of cylinder A .

d - If the diameter of cylinder B is 151 mm , then find the diameter of A .

Thank u so much in advance !!!
Hello,

I've attached a screenshot of the calculations

4. earboth BIG BIG THANKS !!!!!!!!!