All Questions
Tagged with birthday discrete-mathematics
19
questions
2
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119
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What is the limit probability an element of $x \in S$ belongs to $f^n(S)$, for $n \to \infty$?
Let $S$ be a finite set of $|S|=n$ elements and $F$ be the set of all functions $f:S\rightarrow S$.
It's easy to demonstrate that the integer sequence $\{c_i\} = |{\rm Im}(f^i)|$:
is non increasing;
...
- 21
1
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2
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158
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Birthday problem with shared birthdays among males and female students
There are $m$ male and $f$ female students in a class (where $m$ and $f$ are each less than 365) What is the probability that a male student shares a birthday with a female student?
I have attempted ...
- 1,834
1
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1
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106
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At least how many residents of the country have the same birthday?
I am trying to solve a pigeonhole question in discrete mathematics.
Let's suppose that a country has 11.000.000 people. At least how many residents of the country have the same birthday?
Take into ...
- 497
4
votes
1
answer
503
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Random Variable - Birthday Problem
How many people are needed so that the probability that at least two of them were born on the same day of the week is at least 1/2? (Assume that the days of the week are equally likely to be the ...
- 97
0
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0
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Question about Birthday Problem [duplicate]
My first intuition was to think $P(\{\text{No two bdays coincide}\}) = \displaystyle{\frac{\binom{365}{n}}{365}}$ given $365 \ge n$. Turns out $P(\{\text{No two bdays coincide}\}) = \displaystyle{\...
0
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1
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92
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What is the expected number of days of the year that are a birthday of at least one of n people?
I am new to probability and am just learning about the birthday problem. There is a sample problem that asks among a group of $n$ unrelated people, what is the expected number of days of the year that ...
- 41
3
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1
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Is there a generalized solution to the birthday problem? [duplicate]
The problem of the calculating the probability that there is a birthday shared by at least 2 people in a group of size n is well known. I am wondering if there is a way of finding the probability of ...
1
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1
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83
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Is there a way to *directly* calculate the probability that two or more people (of four chosen) have the same birthday?
You randomly choose four people. What is the probability that two or more of them have the same birthday? It's easy to calculate the probability that none of them have the same birthday (($365*364*363*...
- 2,331
1
vote
2
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72
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Probability of distribution using a discrete random function
Problem:
Given P persons (say 1000) distribued among N rooms (say 50) using a discrete random distribution function.
What would be the probability of a room having at least K persons (say 30 or more ...
- 123
2
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0
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299
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how many persons need to be in one room , so AT LEAST 3 people have the same Birth MONTH?
how many persons need to be in one room , so AT LEAST 3 people have the same Birth MONTH ?
Another Answer i suggest : (correct me if i'm wrong) there should be 15 People at least , because if there's ...
- 23
0
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1
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28
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Distribution for count of unique elements
Consider the selection, with replacement, of $N$ elements uniformly at random from $\{1, 2,\dots, M\}$. From the selected elements, count the number of unique elements.
Does the distribution of this ...
- 175
0
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2
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1k
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Probability of at least $3$ people sharing the same birthday in a group of $n$ people
Disclaimer: I've seen posts with good answers for the case of "at least $2$ people", or "exactly $2$ people". Posts with "at least $k$ people" usually suppose that the mutual birthday is a fixed day (...
- 208
0
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1
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265
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Birthday Problem Probability
How would I calculate the probability of atleast 2 people having the same birthday given a group of 3 using counting principles. I know that using P(same bday) = 1 - P(not same bday). I calculated ...
- 142
3
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2
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Birthday problem with at least 3 people
Question: whats the probability that at least 3 out of a group of n people have the same birthday.
I am confused as to where to start. I know that it would be complementary probability, but even then ...
- 105
0
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1
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158
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Discrete Math Birthday Probability Scenario - Exceeding probability of 1/2
Find the smallest number of people you need to choose at random so that the probability that at least one has a birthday today exceeds 1/2.
About all I have so far is that (assuming a 365 day ...
- 33