4 letters and 4 numbers to choose from, whats the probability that a specific 4 letter word is chosen
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We have 4 letters I, D, L, E and 4 numbers 1, 9, 8, 7 to create an 8 character password. What is the probability that in a randomly created password, "IDLE" appears?
(Order matters. ex: idle is different from ldie)
probability
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add a comment |
$begingroup$
We have 4 letters I, D, L, E and 4 numbers 1, 9, 8, 7 to create an 8 character password. What is the probability that in a randomly created password, "IDLE" appears?
(Order matters. ex: idle is different from ldie)
probability
New contributor
Priscilla96 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
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2
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Welcome to Math.SE! Please read this post and the others there for information on writing a good question for this site. In particular, people will be more willing to help if you edit your question to include some motivation, and an explanation of your own attempts.
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– GNUSupporter 8964民主女神 地下教會
7 hours ago
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Can a character be used more than once?
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– saulspatz
7 hours ago
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Does "ID1987LE" count or must the four characters be consecutive ?
$endgroup$
– WW1
7 hours ago
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Is the password is "IDLE1987"? I mean do you want the probability of getting the password "IDLE1987" from all possible combinations?
$endgroup$
– Sujit Bhattacharyya
7 hours ago
add a comment |
$begingroup$
We have 4 letters I, D, L, E and 4 numbers 1, 9, 8, 7 to create an 8 character password. What is the probability that in a randomly created password, "IDLE" appears?
(Order matters. ex: idle is different from ldie)
probability
New contributor
Priscilla96 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
$endgroup$
We have 4 letters I, D, L, E and 4 numbers 1, 9, 8, 7 to create an 8 character password. What is the probability that in a randomly created password, "IDLE" appears?
(Order matters. ex: idle is different from ldie)
probability
probability
New contributor
Priscilla96 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
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edited 7 hours ago
GNUSupporter 8964民主女神 地下教會
12.8k72445
12.8k72445
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Priscilla96 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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asked 8 hours ago
Priscilla96Priscilla96
161
161
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Priscilla96 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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New contributor
Priscilla96 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
Priscilla96 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
2
$begingroup$
Welcome to Math.SE! Please read this post and the others there for information on writing a good question for this site. In particular, people will be more willing to help if you edit your question to include some motivation, and an explanation of your own attempts.
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– GNUSupporter 8964民主女神 地下教會
7 hours ago
$begingroup$
Can a character be used more than once?
$endgroup$
– saulspatz
7 hours ago
$begingroup$
Does "ID1987LE" count or must the four characters be consecutive ?
$endgroup$
– WW1
7 hours ago
$begingroup$
Is the password is "IDLE1987"? I mean do you want the probability of getting the password "IDLE1987" from all possible combinations?
$endgroup$
– Sujit Bhattacharyya
7 hours ago
add a comment |
2
$begingroup$
Welcome to Math.SE! Please read this post and the others there for information on writing a good question for this site. In particular, people will be more willing to help if you edit your question to include some motivation, and an explanation of your own attempts.
$endgroup$
– GNUSupporter 8964民主女神 地下教會
7 hours ago
$begingroup$
Can a character be used more than once?
$endgroup$
– saulspatz
7 hours ago
$begingroup$
Does "ID1987LE" count or must the four characters be consecutive ?
$endgroup$
– WW1
7 hours ago
$begingroup$
Is the password is "IDLE1987"? I mean do you want the probability of getting the password "IDLE1987" from all possible combinations?
$endgroup$
– Sujit Bhattacharyya
7 hours ago
2
2
$begingroup$
Welcome to Math.SE! Please read this post and the others there for information on writing a good question for this site. In particular, people will be more willing to help if you edit your question to include some motivation, and an explanation of your own attempts.
$endgroup$
– GNUSupporter 8964民主女神 地下教會
7 hours ago
$begingroup$
Welcome to Math.SE! Please read this post and the others there for information on writing a good question for this site. In particular, people will be more willing to help if you edit your question to include some motivation, and an explanation of your own attempts.
$endgroup$
– GNUSupporter 8964民主女神 地下教會
7 hours ago
$begingroup$
Can a character be used more than once?
$endgroup$
– saulspatz
7 hours ago
$begingroup$
Can a character be used more than once?
$endgroup$
– saulspatz
7 hours ago
$begingroup$
Does "ID1987LE" count or must the four characters be consecutive ?
$endgroup$
– WW1
7 hours ago
$begingroup$
Does "ID1987LE" count or must the four characters be consecutive ?
$endgroup$
– WW1
7 hours ago
$begingroup$
Is the password is "IDLE1987"? I mean do you want the probability of getting the password "IDLE1987" from all possible combinations?
$endgroup$
– Sujit Bhattacharyya
7 hours ago
$begingroup$
Is the password is "IDLE1987"? I mean do you want the probability of getting the password "IDLE1987" from all possible combinations?
$endgroup$
– Sujit Bhattacharyya
7 hours ago
add a comment |
2 Answers
2
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The number of all possible passwords with these 8 characters is 8!.
The number of passwords where I,D,L,E appear consecutively is equal to the number of possible positions of IDLE within the password (which is 4) times the number of possible permutations of the remaining 4 characters (which is 4!).
So the probability will be $frac{4(4!)}{8!}$.
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1
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the number of possible positions of IDLE within the password should be 5.
$endgroup$
– Julius
5 hours ago
add a comment |
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Your question can be interpreted in two different ways. The way of choosing the password as a random permutation of "IDLE1987" was dealt in the answer by Zaeem Hussein. Here I deal with the other interpretation, where the letters of the password are chosen independently and uniformly from $8$ available ones.
Suppose, we generated a password and a subword "IDLE" appeared in it. If the password has length 8, then the letter 'I' of "IDLE" is either first in the passport, or second, or third, or fourth ($4$ different cases). In any of those cases only it and the $3$ letters after it matter, so the probability of each of these situations is $frac{1}{8^4}$. However, one does not simply sum them up in order to get the answer, as then we will count one possible password twice. That is "IDLEIDLE". Its probability is $frac{1}{8^8}$. So the final probability is $frac{4}{8^4} - frac{1}{8^8} = frac{16383}{16777216}$
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2 Answers
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2 Answers
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$begingroup$
The number of all possible passwords with these 8 characters is 8!.
The number of passwords where I,D,L,E appear consecutively is equal to the number of possible positions of IDLE within the password (which is 4) times the number of possible permutations of the remaining 4 characters (which is 4!).
So the probability will be $frac{4(4!)}{8!}$.
$endgroup$
1
$begingroup$
the number of possible positions of IDLE within the password should be 5.
$endgroup$
– Julius
5 hours ago
add a comment |
$begingroup$
The number of all possible passwords with these 8 characters is 8!.
The number of passwords where I,D,L,E appear consecutively is equal to the number of possible positions of IDLE within the password (which is 4) times the number of possible permutations of the remaining 4 characters (which is 4!).
So the probability will be $frac{4(4!)}{8!}$.
$endgroup$
1
$begingroup$
the number of possible positions of IDLE within the password should be 5.
$endgroup$
– Julius
5 hours ago
add a comment |
$begingroup$
The number of all possible passwords with these 8 characters is 8!.
The number of passwords where I,D,L,E appear consecutively is equal to the number of possible positions of IDLE within the password (which is 4) times the number of possible permutations of the remaining 4 characters (which is 4!).
So the probability will be $frac{4(4!)}{8!}$.
$endgroup$
The number of all possible passwords with these 8 characters is 8!.
The number of passwords where I,D,L,E appear consecutively is equal to the number of possible positions of IDLE within the password (which is 4) times the number of possible permutations of the remaining 4 characters (which is 4!).
So the probability will be $frac{4(4!)}{8!}$.
answered 7 hours ago
Zaeem HussainZaeem Hussain
785
785
1
$begingroup$
the number of possible positions of IDLE within the password should be 5.
$endgroup$
– Julius
5 hours ago
add a comment |
1
$begingroup$
the number of possible positions of IDLE within the password should be 5.
$endgroup$
– Julius
5 hours ago
1
1
$begingroup$
the number of possible positions of IDLE within the password should be 5.
$endgroup$
– Julius
5 hours ago
$begingroup$
the number of possible positions of IDLE within the password should be 5.
$endgroup$
– Julius
5 hours ago
add a comment |
$begingroup$
Your question can be interpreted in two different ways. The way of choosing the password as a random permutation of "IDLE1987" was dealt in the answer by Zaeem Hussein. Here I deal with the other interpretation, where the letters of the password are chosen independently and uniformly from $8$ available ones.
Suppose, we generated a password and a subword "IDLE" appeared in it. If the password has length 8, then the letter 'I' of "IDLE" is either first in the passport, or second, or third, or fourth ($4$ different cases). In any of those cases only it and the $3$ letters after it matter, so the probability of each of these situations is $frac{1}{8^4}$. However, one does not simply sum them up in order to get the answer, as then we will count one possible password twice. That is "IDLEIDLE". Its probability is $frac{1}{8^8}$. So the final probability is $frac{4}{8^4} - frac{1}{8^8} = frac{16383}{16777216}$
$endgroup$
add a comment |
$begingroup$
Your question can be interpreted in two different ways. The way of choosing the password as a random permutation of "IDLE1987" was dealt in the answer by Zaeem Hussein. Here I deal with the other interpretation, where the letters of the password are chosen independently and uniformly from $8$ available ones.
Suppose, we generated a password and a subword "IDLE" appeared in it. If the password has length 8, then the letter 'I' of "IDLE" is either first in the passport, or second, or third, or fourth ($4$ different cases). In any of those cases only it and the $3$ letters after it matter, so the probability of each of these situations is $frac{1}{8^4}$. However, one does not simply sum them up in order to get the answer, as then we will count one possible password twice. That is "IDLEIDLE". Its probability is $frac{1}{8^8}$. So the final probability is $frac{4}{8^4} - frac{1}{8^8} = frac{16383}{16777216}$
$endgroup$
add a comment |
$begingroup$
Your question can be interpreted in two different ways. The way of choosing the password as a random permutation of "IDLE1987" was dealt in the answer by Zaeem Hussein. Here I deal with the other interpretation, where the letters of the password are chosen independently and uniformly from $8$ available ones.
Suppose, we generated a password and a subword "IDLE" appeared in it. If the password has length 8, then the letter 'I' of "IDLE" is either first in the passport, or second, or third, or fourth ($4$ different cases). In any of those cases only it and the $3$ letters after it matter, so the probability of each of these situations is $frac{1}{8^4}$. However, one does not simply sum them up in order to get the answer, as then we will count one possible password twice. That is "IDLEIDLE". Its probability is $frac{1}{8^8}$. So the final probability is $frac{4}{8^4} - frac{1}{8^8} = frac{16383}{16777216}$
$endgroup$
Your question can be interpreted in two different ways. The way of choosing the password as a random permutation of "IDLE1987" was dealt in the answer by Zaeem Hussein. Here I deal with the other interpretation, where the letters of the password are chosen independently and uniformly from $8$ available ones.
Suppose, we generated a password and a subword "IDLE" appeared in it. If the password has length 8, then the letter 'I' of "IDLE" is either first in the passport, or second, or third, or fourth ($4$ different cases). In any of those cases only it and the $3$ letters after it matter, so the probability of each of these situations is $frac{1}{8^4}$. However, one does not simply sum them up in order to get the answer, as then we will count one possible password twice. That is "IDLEIDLE". Its probability is $frac{1}{8^8}$. So the final probability is $frac{4}{8^4} - frac{1}{8^8} = frac{16383}{16777216}$
edited 7 hours ago
answered 7 hours ago
Yanior WegYanior Weg
1,76311138
1,76311138
add a comment |
add a comment |
Priscilla96 is a new contributor. Be nice, and check out our Code of Conduct.
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2
$begingroup$
Welcome to Math.SE! Please read this post and the others there for information on writing a good question for this site. In particular, people will be more willing to help if you edit your question to include some motivation, and an explanation of your own attempts.
$endgroup$
– GNUSupporter 8964民主女神 地下教會
7 hours ago
$begingroup$
Can a character be used more than once?
$endgroup$
– saulspatz
7 hours ago
$begingroup$
Does "ID1987LE" count or must the four characters be consecutive ?
$endgroup$
– WW1
7 hours ago
$begingroup$
Is the password is "IDLE1987"? I mean do you want the probability of getting the password "IDLE1987" from all possible combinations?
$endgroup$
– Sujit Bhattacharyya
7 hours ago