Probability of more than n machines down any hour?












4












$begingroup$


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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$endgroup$








  • 2




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






  • 1




    $begingroup$
    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 $t$?
    $endgroup$
    – SmileyCraft
    Jan 4 at 4:21










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










  • $begingroup$
    @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?
    $endgroup$
    – Vance
    Jan 4 at 4:36










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
















4












$begingroup$


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











$endgroup$








  • 2




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






  • 1




    $begingroup$
    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 $t$?
    $endgroup$
    – SmileyCraft
    Jan 4 at 4:21










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










  • $begingroup$
    @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?
    $endgroup$
    – Vance
    Jan 4 at 4:36










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














4












4








4


2



$begingroup$


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











$endgroup$




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















share|cite|improve this question













share|cite|improve this question




share|cite|improve this question








edited Jan 4 at 15:55







Vance

















asked Jan 4 at 4:17









VanceVance

212




212








  • 2




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






  • 1




    $begingroup$
    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 $t$?
    $endgroup$
    – SmileyCraft
    Jan 4 at 4:21










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










  • $begingroup$
    @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?
    $endgroup$
    – Vance
    Jan 4 at 4:36










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














  • 2




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






  • 1




    $begingroup$
    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 $t$?
    $endgroup$
    – SmileyCraft
    Jan 4 at 4:21










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










  • $begingroup$
    @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?
    $endgroup$
    – Vance
    Jan 4 at 4:36










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








2




2




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




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




1




1




$begingroup$
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 $t$?
$endgroup$
– SmileyCraft
Jan 4 at 4:21




$begingroup$
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 $t$?
$endgroup$
– SmileyCraft
Jan 4 at 4:21












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




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












$begingroup$
@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?
$endgroup$
– Vance
Jan 4 at 4:36




$begingroup$
@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?
$endgroup$
– Vance
Jan 4 at 4:36












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




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










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