Arrangements of MISSISSIPPI with all S's and P's separated
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If the all S,P are separated in the word MISSISSIPPI then the total possible arrangements are $kfrac {10!}{4!.4!} $ then value of k is? Now all S,P are separated so we can have slash method. Thus they can be placed alternatively in $6! $ ways and rest 5 can be placed in $5! $ ways. Thus we equate to get $$6!.5!=kfrac {10!}{4!.4!} $$ to get $k=13.7$ while $k=4/3$ .Where is my mistake Thanks
combinatorics
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add a comment |
$begingroup$
If the all S,P are separated in the word MISSISSIPPI then the total possible arrangements are $kfrac {10!}{4!.4!} $ then value of k is? Now all S,P are separated so we can have slash method. Thus they can be placed alternatively in $6! $ ways and rest 5 can be placed in $5! $ ways. Thus we equate to get $$6!.5!=kfrac {10!}{4!.4!} $$ to get $k=13.7$ while $k=4/3$ .Where is my mistake Thanks
combinatorics
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Can a S and a P occur together ?
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– Shailesh
Sep 6 '16 at 10:03
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Yes they can as nothing is mentioned in the question
$endgroup$
– Archis Welankar
Sep 6 '16 at 10:11
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Your book answer is incorrect. $k = 1$ is correct as pointed out by the answer by trueblueanil.
$endgroup$
– Shailesh
Sep 7 '16 at 5:54
add a comment |
$begingroup$
If the all S,P are separated in the word MISSISSIPPI then the total possible arrangements are $kfrac {10!}{4!.4!} $ then value of k is? Now all S,P are separated so we can have slash method. Thus they can be placed alternatively in $6! $ ways and rest 5 can be placed in $5! $ ways. Thus we equate to get $$6!.5!=kfrac {10!}{4!.4!} $$ to get $k=13.7$ while $k=4/3$ .Where is my mistake Thanks
combinatorics
$endgroup$
If the all S,P are separated in the word MISSISSIPPI then the total possible arrangements are $kfrac {10!}{4!.4!} $ then value of k is? Now all S,P are separated so we can have slash method. Thus they can be placed alternatively in $6! $ ways and rest 5 can be placed in $5! $ ways. Thus we equate to get $$6!.5!=kfrac {10!}{4!.4!} $$ to get $k=13.7$ while $k=4/3$ .Where is my mistake Thanks
combinatorics
combinatorics
edited Sep 29 '16 at 14:35
Shailesh
3,99692134
3,99692134
asked Sep 6 '16 at 9:52
Archis WelankarArchis Welankar
12.1k41641
12.1k41641
$begingroup$
Can a S and a P occur together ?
$endgroup$
– Shailesh
Sep 6 '16 at 10:03
$begingroup$
Yes they can as nothing is mentioned in the question
$endgroup$
– Archis Welankar
Sep 6 '16 at 10:11
$begingroup$
Your book answer is incorrect. $k = 1$ is correct as pointed out by the answer by trueblueanil.
$endgroup$
– Shailesh
Sep 7 '16 at 5:54
add a comment |
$begingroup$
Can a S and a P occur together ?
$endgroup$
– Shailesh
Sep 6 '16 at 10:03
$begingroup$
Yes they can as nothing is mentioned in the question
$endgroup$
– Archis Welankar
Sep 6 '16 at 10:11
$begingroup$
Your book answer is incorrect. $k = 1$ is correct as pointed out by the answer by trueblueanil.
$endgroup$
– Shailesh
Sep 7 '16 at 5:54
$begingroup$
Can a S and a P occur together ?
$endgroup$
– Shailesh
Sep 6 '16 at 10:03
$begingroup$
Can a S and a P occur together ?
$endgroup$
– Shailesh
Sep 6 '16 at 10:03
$begingroup$
Yes they can as nothing is mentioned in the question
$endgroup$
– Archis Welankar
Sep 6 '16 at 10:11
$begingroup$
Yes they can as nothing is mentioned in the question
$endgroup$
– Archis Welankar
Sep 6 '16 at 10:11
$begingroup$
Your book answer is incorrect. $k = 1$ is correct as pointed out by the answer by trueblueanil.
$endgroup$
– Shailesh
Sep 7 '16 at 5:54
$begingroup$
Your book answer is incorrect. $k = 1$ is correct as pointed out by the answer by trueblueanil.
$endgroup$
– Shailesh
Sep 7 '16 at 5:54
add a comment |
1 Answer
1
active
oldest
votes
$begingroup$
Leaving out the $S's$ for the moment, there are $frac{7!}{4!2!} = 105$ permutations of $PPMIIII$
Of these $frac{6!}{4!} = 30$ will have the $P's$ together, thus $75$ will have the $P's$ apart.
For the together cases, we need to borrow an $S$ to separate them, e.g. $boxed{PSP}MIIII$
The remaining $3; S's$ can be inserted in the gaps between units (including ends) in $binom73$ ways
For cases with $P's$ already separate, e.g. PMPIIII, the $4; S's$ can be inserted similarly in $binom84$ ways.
Thus permissible permutations $= 30binom73 + 75binom84 = 6300$
For better or worse, this give a value of $k=1$
Use of heavy artillery
To make assurance doubly sure, I have used Jair Taylor's formula to confirm the answer.
Define polynomials for $kgeq 1$ by $q_k(x) =
sum_{i=1}^k frac{(-1)^{i-k}}{i!} {k-1 choose i-1}x^i$.
e.g. for $k=2, q_2(x)$ works out to ${(x^2-2x)}/2!$
For the nonce, we shall take the $I's$ to be distinct, divide by $4!$ at the end of the calculations. So we have five distinct alphabets, one of length $2$ and one of length $4$
The number of permutations will be given by
$$int_0^infty prod_j q_{k_j}(x), e^{-x},dx.$$
Wolframalpha gives the answer as $151,200$
Dividing by $4!$ to take care of the $4 I's$, we again get the answer of $6300$
$endgroup$
$begingroup$
Your argument is flawless - not checked the 'heavy artillery' one. Also one Aditya Raut confirmed 6300 with Python code. +1 for all the efforts.
$endgroup$
– Shailesh
Sep 7 '16 at 5:52
$begingroup$
Im just a beginner so I didnt see you computer techniques but the first part os awesom thanks
$endgroup$
– Archis Welankar
Sep 7 '16 at 10:49
$begingroup$
@ArchisWelankar Then upvote it too !
$endgroup$
– Shailesh
Sep 7 '16 at 11:35
$begingroup$
You're welcome !
$endgroup$
– true blue anil
Sep 7 '16 at 14:30
add a comment |
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1 Answer
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1 Answer
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oldest
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$begingroup$
Leaving out the $S's$ for the moment, there are $frac{7!}{4!2!} = 105$ permutations of $PPMIIII$
Of these $frac{6!}{4!} = 30$ will have the $P's$ together, thus $75$ will have the $P's$ apart.
For the together cases, we need to borrow an $S$ to separate them, e.g. $boxed{PSP}MIIII$
The remaining $3; S's$ can be inserted in the gaps between units (including ends) in $binom73$ ways
For cases with $P's$ already separate, e.g. PMPIIII, the $4; S's$ can be inserted similarly in $binom84$ ways.
Thus permissible permutations $= 30binom73 + 75binom84 = 6300$
For better or worse, this give a value of $k=1$
Use of heavy artillery
To make assurance doubly sure, I have used Jair Taylor's formula to confirm the answer.
Define polynomials for $kgeq 1$ by $q_k(x) =
sum_{i=1}^k frac{(-1)^{i-k}}{i!} {k-1 choose i-1}x^i$.
e.g. for $k=2, q_2(x)$ works out to ${(x^2-2x)}/2!$
For the nonce, we shall take the $I's$ to be distinct, divide by $4!$ at the end of the calculations. So we have five distinct alphabets, one of length $2$ and one of length $4$
The number of permutations will be given by
$$int_0^infty prod_j q_{k_j}(x), e^{-x},dx.$$
Wolframalpha gives the answer as $151,200$
Dividing by $4!$ to take care of the $4 I's$, we again get the answer of $6300$
$endgroup$
$begingroup$
Your argument is flawless - not checked the 'heavy artillery' one. Also one Aditya Raut confirmed 6300 with Python code. +1 for all the efforts.
$endgroup$
– Shailesh
Sep 7 '16 at 5:52
$begingroup$
Im just a beginner so I didnt see you computer techniques but the first part os awesom thanks
$endgroup$
– Archis Welankar
Sep 7 '16 at 10:49
$begingroup$
@ArchisWelankar Then upvote it too !
$endgroup$
– Shailesh
Sep 7 '16 at 11:35
$begingroup$
You're welcome !
$endgroup$
– true blue anil
Sep 7 '16 at 14:30
add a comment |
$begingroup$
Leaving out the $S's$ for the moment, there are $frac{7!}{4!2!} = 105$ permutations of $PPMIIII$
Of these $frac{6!}{4!} = 30$ will have the $P's$ together, thus $75$ will have the $P's$ apart.
For the together cases, we need to borrow an $S$ to separate them, e.g. $boxed{PSP}MIIII$
The remaining $3; S's$ can be inserted in the gaps between units (including ends) in $binom73$ ways
For cases with $P's$ already separate, e.g. PMPIIII, the $4; S's$ can be inserted similarly in $binom84$ ways.
Thus permissible permutations $= 30binom73 + 75binom84 = 6300$
For better or worse, this give a value of $k=1$
Use of heavy artillery
To make assurance doubly sure, I have used Jair Taylor's formula to confirm the answer.
Define polynomials for $kgeq 1$ by $q_k(x) =
sum_{i=1}^k frac{(-1)^{i-k}}{i!} {k-1 choose i-1}x^i$.
e.g. for $k=2, q_2(x)$ works out to ${(x^2-2x)}/2!$
For the nonce, we shall take the $I's$ to be distinct, divide by $4!$ at the end of the calculations. So we have five distinct alphabets, one of length $2$ and one of length $4$
The number of permutations will be given by
$$int_0^infty prod_j q_{k_j}(x), e^{-x},dx.$$
Wolframalpha gives the answer as $151,200$
Dividing by $4!$ to take care of the $4 I's$, we again get the answer of $6300$
$endgroup$
$begingroup$
Your argument is flawless - not checked the 'heavy artillery' one. Also one Aditya Raut confirmed 6300 with Python code. +1 for all the efforts.
$endgroup$
– Shailesh
Sep 7 '16 at 5:52
$begingroup$
Im just a beginner so I didnt see you computer techniques but the first part os awesom thanks
$endgroup$
– Archis Welankar
Sep 7 '16 at 10:49
$begingroup$
@ArchisWelankar Then upvote it too !
$endgroup$
– Shailesh
Sep 7 '16 at 11:35
$begingroup$
You're welcome !
$endgroup$
– true blue anil
Sep 7 '16 at 14:30
add a comment |
$begingroup$
Leaving out the $S's$ for the moment, there are $frac{7!}{4!2!} = 105$ permutations of $PPMIIII$
Of these $frac{6!}{4!} = 30$ will have the $P's$ together, thus $75$ will have the $P's$ apart.
For the together cases, we need to borrow an $S$ to separate them, e.g. $boxed{PSP}MIIII$
The remaining $3; S's$ can be inserted in the gaps between units (including ends) in $binom73$ ways
For cases with $P's$ already separate, e.g. PMPIIII, the $4; S's$ can be inserted similarly in $binom84$ ways.
Thus permissible permutations $= 30binom73 + 75binom84 = 6300$
For better or worse, this give a value of $k=1$
Use of heavy artillery
To make assurance doubly sure, I have used Jair Taylor's formula to confirm the answer.
Define polynomials for $kgeq 1$ by $q_k(x) =
sum_{i=1}^k frac{(-1)^{i-k}}{i!} {k-1 choose i-1}x^i$.
e.g. for $k=2, q_2(x)$ works out to ${(x^2-2x)}/2!$
For the nonce, we shall take the $I's$ to be distinct, divide by $4!$ at the end of the calculations. So we have five distinct alphabets, one of length $2$ and one of length $4$
The number of permutations will be given by
$$int_0^infty prod_j q_{k_j}(x), e^{-x},dx.$$
Wolframalpha gives the answer as $151,200$
Dividing by $4!$ to take care of the $4 I's$, we again get the answer of $6300$
$endgroup$
Leaving out the $S's$ for the moment, there are $frac{7!}{4!2!} = 105$ permutations of $PPMIIII$
Of these $frac{6!}{4!} = 30$ will have the $P's$ together, thus $75$ will have the $P's$ apart.
For the together cases, we need to borrow an $S$ to separate them, e.g. $boxed{PSP}MIIII$
The remaining $3; S's$ can be inserted in the gaps between units (including ends) in $binom73$ ways
For cases with $P's$ already separate, e.g. PMPIIII, the $4; S's$ can be inserted similarly in $binom84$ ways.
Thus permissible permutations $= 30binom73 + 75binom84 = 6300$
For better or worse, this give a value of $k=1$
Use of heavy artillery
To make assurance doubly sure, I have used Jair Taylor's formula to confirm the answer.
Define polynomials for $kgeq 1$ by $q_k(x) =
sum_{i=1}^k frac{(-1)^{i-k}}{i!} {k-1 choose i-1}x^i$.
e.g. for $k=2, q_2(x)$ works out to ${(x^2-2x)}/2!$
For the nonce, we shall take the $I's$ to be distinct, divide by $4!$ at the end of the calculations. So we have five distinct alphabets, one of length $2$ and one of length $4$
The number of permutations will be given by
$$int_0^infty prod_j q_{k_j}(x), e^{-x},dx.$$
Wolframalpha gives the answer as $151,200$
Dividing by $4!$ to take care of the $4 I's$, we again get the answer of $6300$
edited Dec 2 '18 at 12:01
amWhy
1
1
answered Sep 6 '16 at 12:07
true blue aniltrue blue anil
20.5k11941
20.5k11941
$begingroup$
Your argument is flawless - not checked the 'heavy artillery' one. Also one Aditya Raut confirmed 6300 with Python code. +1 for all the efforts.
$endgroup$
– Shailesh
Sep 7 '16 at 5:52
$begingroup$
Im just a beginner so I didnt see you computer techniques but the first part os awesom thanks
$endgroup$
– Archis Welankar
Sep 7 '16 at 10:49
$begingroup$
@ArchisWelankar Then upvote it too !
$endgroup$
– Shailesh
Sep 7 '16 at 11:35
$begingroup$
You're welcome !
$endgroup$
– true blue anil
Sep 7 '16 at 14:30
add a comment |
$begingroup$
Your argument is flawless - not checked the 'heavy artillery' one. Also one Aditya Raut confirmed 6300 with Python code. +1 for all the efforts.
$endgroup$
– Shailesh
Sep 7 '16 at 5:52
$begingroup$
Im just a beginner so I didnt see you computer techniques but the first part os awesom thanks
$endgroup$
– Archis Welankar
Sep 7 '16 at 10:49
$begingroup$
@ArchisWelankar Then upvote it too !
$endgroup$
– Shailesh
Sep 7 '16 at 11:35
$begingroup$
You're welcome !
$endgroup$
– true blue anil
Sep 7 '16 at 14:30
$begingroup$
Your argument is flawless - not checked the 'heavy artillery' one. Also one Aditya Raut confirmed 6300 with Python code. +1 for all the efforts.
$endgroup$
– Shailesh
Sep 7 '16 at 5:52
$begingroup$
Your argument is flawless - not checked the 'heavy artillery' one. Also one Aditya Raut confirmed 6300 with Python code. +1 for all the efforts.
$endgroup$
– Shailesh
Sep 7 '16 at 5:52
$begingroup$
Im just a beginner so I didnt see you computer techniques but the first part os awesom thanks
$endgroup$
– Archis Welankar
Sep 7 '16 at 10:49
$begingroup$
Im just a beginner so I didnt see you computer techniques but the first part os awesom thanks
$endgroup$
– Archis Welankar
Sep 7 '16 at 10:49
$begingroup$
@ArchisWelankar Then upvote it too !
$endgroup$
– Shailesh
Sep 7 '16 at 11:35
$begingroup$
@ArchisWelankar Then upvote it too !
$endgroup$
– Shailesh
Sep 7 '16 at 11:35
$begingroup$
You're welcome !
$endgroup$
– true blue anil
Sep 7 '16 at 14:30
$begingroup$
You're welcome !
$endgroup$
– true blue anil
Sep 7 '16 at 14:30
add a comment |
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$begingroup$
Can a S and a P occur together ?
$endgroup$
– Shailesh
Sep 6 '16 at 10:03
$begingroup$
Yes they can as nothing is mentioned in the question
$endgroup$
– Archis Welankar
Sep 6 '16 at 10:11
$begingroup$
Your book answer is incorrect. $k = 1$ is correct as pointed out by the answer by trueblueanil.
$endgroup$
– Shailesh
Sep 7 '16 at 5:54