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A sheet of paper 8 units long and 6 units wide is rolled [#permalink]
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30 Dec 2003, 09:57
This topic is locked. If you want to discuss this question please repost it in the respective forum. A sheet of paper 8 units long and 6 units wide is rolled into a cylinder 8 units in height. What is the volume of the cylinder?
48/pi
72/pi
24/pi
9/pi
96/pi
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shubhangi



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Location: USA

With assumptions
circumfrence = 2*pi*r = 6
therefore r = 3/pi
volume = 8*pi*r^2 = 8 *pi*(9/pi^2) = 72/pi
B?



Director
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Okay, Shubanghi  now you tell us what the Surface Area of the cylinder is with explanation! (let Shubanghi answer this please!)



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Well , i am not good in Geometry at all..but still i will give a try.
its asks the volume..so we must find out the radius of the cyclinder.Since the width is 6 ..the circumfernece should be 6 too..then find the radius.
6=2*pi*r..tf..(6/2*pi)=(2*pi*r/2*pi) = 3/pi=r......(1)
volume = pi*r^2 *h
so pi*3/pi*3/pi*8=72/pi
...
Geo makes me really mad
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shubhangi



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okay now surface area of cyclinder is =2*pi r*h +2*pi*r^2
so 2*pi*3/pi*8 + 2*pi*3*pi*3/pi = 66/pi..right??
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shubhangi



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Good try. Let me leave you with the formula: SA Cylinder = 2 Circles + Rectangle: Thus, 2(Pi*r^2) + 2 pi*r*h
Give it a shot!
Last edited by Titleist on 30 Dec 2003, 12:16, edited 1 time in total.



Director
Joined: 14 Oct 2003
Posts: 583
Location: On Vacation at My Crawford, Texas Ranch

Shubanghi,
This is how I did it:
SA cylinder = 2prh+2(pi*r^2)
we established that r=3/pi
plug in
2*pi*3/pi*8 + 2(pi*3/pi^2)
48 + 2(9/pi) = 48 + 18/pi = 48pi +18



Director
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Okay Shubanghi,
A tougher question for you: this would be considered a difficult question.
If the surface area of a cylinder is 400pi feet and the height of the cylinder is 17 feet, then what is the diameter of this cylinder's circular base?
a)14
b)15.24
c)15.9
d)16
e)16.33
Once you solved this problem, you'll have mastered GMAT cylinder problems!



Director
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No, try backsolving if you can.



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Wow, that pix is way too big Titleist. I understand your promotion to VP but still...
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Paul



Director
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Ditto on the Titleist avatar.
I could wretch!



Senior Manager
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Location: dallas , tx

making me nervous.. .what is the right answer
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shubhangi



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"I didn't tell her to lie under deposition  I told her to lie there in that position!!!!"
Bubba
Last edited by Titleist on 30 Dec 2003, 13:46, edited 1 time in total.



Director
Joined: 14 Oct 2003
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Location: On Vacation at My Crawford, Texas Ranch

400pi=2pi*r^2+2pi*r*h
given: h=17
thus,
400pi=2pi*r^2+2pi*r17
400pi=2pi(r^2+17r)
200=r^2+17r
0=r^2+17r200
0=(r+25)(r8)
thus r=(25,8)
thus we pick r=8
we're not done yet
d=2r
Thus 16 is your answer!
Last edited by Titleist on 30 Dec 2003, 13:47, edited 1 time in total.



GMAT Club Legend
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That line is from Conan O'Brian Indeed, I got D 16 as well
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Paul



Director
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Yes! You're on fire Paul!



Director
Joined: 14 Oct 2003
Posts: 583
Location: On Vacation at My Crawford, Texas Ranch

One more question and we'll call it a night as far as cylinders are concerned.
A cylindrical storage tank containing the liquid chemical, ammonium xylenesulfonate, is being filled at a rate of pi cubic meters per second. Structural engineers are also working on the tank and they are surveying the dimensions of the tank. The tank stands 10 meters tall. If the tank was empty before being filled and if took 13.5 minutes to fill then what is the diameter of the tank?
a) 8 meters
b) 9 meters
c)12 meters
d)16 meters
e)18 meters



Director
Joined: 13 Nov 2003
Posts: 960
Location: Florida

Titleist wrote: One more question and we'll call it a night as far as cylinders are concerned.
A cylindrical storage tank containing the liquid chemical, ammonium xylenesulfonate, is being filled at a rate of pi cubic meters per second. Structural engineers are also working on the tank and they are surveying the dimensions of the tank. The tank stands 10 meters tall. If the tank was empty before being filled and if took 13.5 minutes to fill then what is the diameter of the tank?
a) 8 meters b) 9 meters c)12 meters d)16 meters e)18 meters
hey, did you write this ques. if yes, where did you get "ammonium xylenesulfonate" ..?? interresting.
anyway, I got 18.



Director
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18 it is. Check the ingredients on your shampoo bottle.



Director
Joined: 13 Nov 2003
Posts: 960
Location: Florida

Titleist wrote: 18 it is. Check the ingredients on your shampoo bottle.
hmmm..that's something to ponder
solution:
vol/time = pi*R^2*H / time = pi
H=10
solve for 2R> Dia







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