Probability of more than n machines down any hour?












4














Suppose we have $N$ identical machines, at any given hour, there's a chance $P$ that any given machine went down. A down machine takes $T$ hours to recover. How do I calculate the chances that in a given longer interval $Y$ (assume $Y >> T$), what are the probability that there exists hour $t$, $0 < t < Y$, such that at $t$ there are more than $R$ machines that are down?










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  • 2




    A Poisson distribution describes this situation.
    – David G. Stork
    Jan 4 at 4:19






  • 1




    Do you want to know the probability more than $R$ machines are down at time $Y$ or the probability that there exists time $0<t<Y$ such that more than $R$ machines are down at time $t$?
    – SmileyCraft
    Jan 4 at 4:21










  • @SmileyCraft, the later, the probability that there exists time 0 < t < Y such that more than R machines are down at time t.
    – Vance
    Jan 4 at 4:27










  • @DavidG.Stork, how would I apply Poisson distribution to this scenario? I can maybe find the average number of machines going down per year based on the P, and calculate the chances for r < R, but that does not necessarily answer if they are concurrent?
    – Vance
    Jan 4 at 4:36










  • This is a Poisson distribution with expected number of faults in a given hour of $P N$. That determines all probabilities.
    – David G. Stork
    Jan 4 at 6:38
















4














Suppose we have $N$ identical machines, at any given hour, there's a chance $P$ that any given machine went down. A down machine takes $T$ hours to recover. How do I calculate the chances that in a given longer interval $Y$ (assume $Y >> T$), what are the probability that there exists hour $t$, $0 < t < Y$, such that at $t$ there are more than $R$ machines that are down?










share|cite|improve this question









New contributor




Vance is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
















  • 2




    A Poisson distribution describes this situation.
    – David G. Stork
    Jan 4 at 4:19






  • 1




    Do you want to know the probability more than $R$ machines are down at time $Y$ or the probability that there exists time $0<t<Y$ such that more than $R$ machines are down at time $t$?
    – SmileyCraft
    Jan 4 at 4:21










  • @SmileyCraft, the later, the probability that there exists time 0 < t < Y such that more than R machines are down at time t.
    – Vance
    Jan 4 at 4:27










  • @DavidG.Stork, how would I apply Poisson distribution to this scenario? I can maybe find the average number of machines going down per year based on the P, and calculate the chances for r < R, but that does not necessarily answer if they are concurrent?
    – Vance
    Jan 4 at 4:36










  • This is a Poisson distribution with expected number of faults in a given hour of $P N$. That determines all probabilities.
    – David G. Stork
    Jan 4 at 6:38














4












4








4


2





Suppose we have $N$ identical machines, at any given hour, there's a chance $P$ that any given machine went down. A down machine takes $T$ hours to recover. How do I calculate the chances that in a given longer interval $Y$ (assume $Y >> T$), what are the probability that there exists hour $t$, $0 < t < Y$, such that at $t$ there are more than $R$ machines that are down?










share|cite|improve this question









New contributor




Vance is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.











Suppose we have $N$ identical machines, at any given hour, there's a chance $P$ that any given machine went down. A down machine takes $T$ hours to recover. How do I calculate the chances that in a given longer interval $Y$ (assume $Y >> T$), what are the probability that there exists hour $t$, $0 < t < Y$, such that at $t$ there are more than $R$ machines that are down?







probability probability-distributions






share|cite|improve this question









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Vance is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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share|cite|improve this question









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Check out our Code of Conduct.









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edited Jan 4 at 15:55







Vance













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asked Jan 4 at 4:17









VanceVance

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Vance is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.






Vance is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.








  • 2




    A Poisson distribution describes this situation.
    – David G. Stork
    Jan 4 at 4:19






  • 1




    Do you want to know the probability more than $R$ machines are down at time $Y$ or the probability that there exists time $0<t<Y$ such that more than $R$ machines are down at time $t$?
    – SmileyCraft
    Jan 4 at 4:21










  • @SmileyCraft, the later, the probability that there exists time 0 < t < Y such that more than R machines are down at time t.
    – Vance
    Jan 4 at 4:27










  • @DavidG.Stork, how would I apply Poisson distribution to this scenario? I can maybe find the average number of machines going down per year based on the P, and calculate the chances for r < R, but that does not necessarily answer if they are concurrent?
    – Vance
    Jan 4 at 4:36










  • This is a Poisson distribution with expected number of faults in a given hour of $P N$. That determines all probabilities.
    – David G. Stork
    Jan 4 at 6:38














  • 2




    A Poisson distribution describes this situation.
    – David G. Stork
    Jan 4 at 4:19






  • 1




    Do you want to know the probability more than $R$ machines are down at time $Y$ or the probability that there exists time $0<t<Y$ such that more than $R$ machines are down at time $t$?
    – SmileyCraft
    Jan 4 at 4:21










  • @SmileyCraft, the later, the probability that there exists time 0 < t < Y such that more than R machines are down at time t.
    – Vance
    Jan 4 at 4:27










  • @DavidG.Stork, how would I apply Poisson distribution to this scenario? I can maybe find the average number of machines going down per year based on the P, and calculate the chances for r < R, but that does not necessarily answer if they are concurrent?
    – Vance
    Jan 4 at 4:36










  • This is a Poisson distribution with expected number of faults in a given hour of $P N$. That determines all probabilities.
    – David G. Stork
    Jan 4 at 6:38








2




2




A Poisson distribution describes this situation.
– David G. Stork
Jan 4 at 4:19




A Poisson distribution describes this situation.
– David G. Stork
Jan 4 at 4:19




1




1




Do you want to know the probability more than $R$ machines are down at time $Y$ or the probability that there exists time $0<t<Y$ such that more than $R$ machines are down at time $t$?
– SmileyCraft
Jan 4 at 4:21




Do you want to know the probability more than $R$ machines are down at time $Y$ or the probability that there exists time $0<t<Y$ such that more than $R$ machines are down at time $t$?
– SmileyCraft
Jan 4 at 4:21












@SmileyCraft, the later, the probability that there exists time 0 < t < Y such that more than R machines are down at time t.
– Vance
Jan 4 at 4:27




@SmileyCraft, the later, the probability that there exists time 0 < t < Y such that more than R machines are down at time t.
– Vance
Jan 4 at 4:27












@DavidG.Stork, how would I apply Poisson distribution to this scenario? I can maybe find the average number of machines going down per year based on the P, and calculate the chances for r < R, but that does not necessarily answer if they are concurrent?
– Vance
Jan 4 at 4:36




@DavidG.Stork, how would I apply Poisson distribution to this scenario? I can maybe find the average number of machines going down per year based on the P, and calculate the chances for r < R, but that does not necessarily answer if they are concurrent?
– Vance
Jan 4 at 4:36












This is a Poisson distribution with expected number of faults in a given hour of $P N$. That determines all probabilities.
– David G. Stork
Jan 4 at 6:38




This is a Poisson distribution with expected number of faults in a given hour of $P N$. That determines all probabilities.
– David G. Stork
Jan 4 at 6:38










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