Math Is Fun Forum
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#1 2014-06-03 13:41:33
Is this problem simple enough?
In how many ways can you choose seven balls from a pool of balls of four colors - red, blue, green, yellow.
The answer is 120 but how do I do it without a gf?
'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.
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#2 2014-06-03 19:16:46
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: Is this problem simple enough?
How many of each are there? It can be done without a gf if you use a certain discrete distribution designed for this type of problem (maybe).
Begin Rant:
but how do I do it without a gf?
I mean really, this is too much. Is not math hard enough without these guys insisting that only certain methods be used and others are in some way inferior? First it was no calculators, then it was no Cas', then without expanding, later no maxima or minima, now it is no gf! I am waiting for the ultimate problem, no calculus, algebra, geometry etc, no thinking and you must solve it while doing a headstand in 2 feet of water. Kaboobly doo doo! I only wished I was a young man again so that I could hand in the most abstract excruciating gf God or I have ever seen, just to vex this problem poser.
End Rant:
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.
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#3 2014-06-03 19:47:14
Re: Is this problem simple enough?
What is a rant?
/-\ fruit seller sells m/-\ngoes. It's summer /-\nd it is /-\lso definitely the best /-\nd most suited time to enjoy the king of fruits /-\nd n/-\ture's delight- M/-\ngoes. /-\nush goes to the m/-\ngo shop to buy some for home. He /-\sks the m/-\ngo seller to give him one kilogr/-\m of m/-\ngoes. The m/-\ngo seller is /-\ good businessm/-\n /-\nd thus s/-\ys th/-\t inste/-\d of one, he h/-\s four different v/-\rieties of m/-\ngoes. When he is questioned by /-\nush /-\s to wh/-\t they /-\re, he is quick to reply - " Neel/-\m , M/-\lgo/-\, Sendur /-\nd D/-\seri". /-\nush is left to buy 7 m/-\ngoes from these /-\s 7 m/-\ngoes m/-\ke up /-\ kilogr/-\m. The fruit seller who is good m/-\them/-\tici/-\n too, offers /-\nush /-\ discount of 50% if he could correctly tell him /-\s to how m/-\ny different w/-\ys /-\re there to purch/-\se this delight. Will you help /-\nush?
Note- This is 100% original. Please like, reshare and follow me if you liked this
P.S: I replaced all A's with '/-\' to make the problem more challenging
Last edited by Agnishom (2014-06-03 19:51:40)
'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.
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#4 2014-06-03 19:52:11
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: Is this problem simple enough?
Def rant:
a lengthy discourse by a single performer, especially if irritated or upset?
loud, declamatory, or extravagant speech; bombast.
sound off, speak up, speak out.
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.
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#5 2014-06-03 19:53:38
Re: Is this problem simple enough?
The original problem is in post 3.
'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.
Offline
#6 2014-06-03 20:00:52
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: Is this problem simple enough?
He wants the number of ways to be 120.
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.
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#7 2014-06-03 20:10:06
Re: Is this problem simple enough?
But that is not my question!
'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.
Offline
#8 2014-06-03 20:12:40
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: Is this problem simple enough?
I know that.
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.
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#9 2014-06-03 20:13:40
Re: Is this problem simple enough?
Can you not do the problem with gf's?
'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.
Offline
#10 2014-06-03 20:21:03
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: Is this problem simple enough?
Where does the 120 come from?
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.
Offline
#11 2014-06-03 20:23:39
Re: Is this problem simple enough?
It is the coefficient x^7 of the taylor expansion of 1/((1-x)^3)
'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.
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#12 2014-06-03 20:25:54
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: Is this problem simple enough?
It is not the coefficient of x^7.
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.
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#13 2014-06-03 20:28:06
Re: Is this problem simple enough?
Coefficient[Series[1/(1 - x)^4, {x, 0, 7}], x^7]'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.
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#14 2014-06-03 20:29:19
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: Is this problem simple enough?
It is the coefficient x^7 of the taylor expansion of 1/((1-x)^3)
Please compare that with post #13.
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.
Offline
#15 2014-06-03 20:32:20
Re: Is this problem simple enough?
That is a typo. So what?
'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.
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#16 2014-06-03 20:35:28
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: Is this problem simple enough?
The answer is
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.
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#17 2014-06-03 20:38:36
Re: Is this problem simple enough?
I am sorry, but I still do not know what you mean.
You could have also said Prime[31] - 7
'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.
Offline
#18 2014-06-03 20:41:58
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: Is this problem simple enough?
I could have but that is the coefficient of x^7 in binomials. Also that was one solution that a program came up with.
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.
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#19 2014-06-03 20:49:12
Re: Is this problem simple enough?
How do you get 10C7?
'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.
Offline
#20 2014-06-03 20:51:02
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: Is this problem simple enough?
4x = 4 choose 1
10x^2 = 5 choose 2
20x^3 = 6 choose 3
.
.
.
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.
Offline
#21 2014-06-03 20:54:18
Re: Is this problem simple enough?
That requires a gf.
'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.
Offline
#22 2014-06-03 21:01:07
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: Is this problem simple enough?
Table[FindInstance[{Binomial[n, a] Binomial[n, b] Binomial[n,c] Binomial[n, d] == 120, a + b + c + d == 7, a >= 0, b >= 0, c >= 0, d >= 0}, {a, b, c, d}, Integers], {n, 2, 12}]In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.
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#23 2014-06-03 21:08:30
Re: Is this problem simple enough?
It says:
{{}, {}, {}, {}, {}, {}, {}, {}, {{a -> 0, b -> 7, c -> 0,
d -> 0}}, {}, {}}'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.
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#24 2014-06-03 21:16:11
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: Is this problem simple enough?
Output is blank except when n = 10.
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.
Offline
#25 2014-06-03 21:16:52
Re: Is this problem simple enough?
I think you have put your replies in the wrong thread 
. Those messages were not directed to you -_-
'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.
Offline