Probability of Poisson Distribution: Nr of Customers in Shop

AI Thread Summary
The discussion focuses on the application of the Poisson distribution to model customer arrivals at a shop, specifically analyzing the probability of future arrivals. For part a), the probability of waiting at least 5 more minutes for another customer, given that one has just arrived and none arrived in the next minute, is calculated to be 0.2636. Part b) involves determining the probability that between 7 and 15 out of 40 non-overlapping 15-minute intervals have at most 2 customers, with the answer derived using the binomial distribution, resulting in a probability of 0.855. The concept of memorylessness in Poisson processes is briefly mentioned as relevant to the first question. Overall, the discussion emphasizes understanding and applying statistical distributions to real-world scenarios.
pinto89a
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Nr of customers arriving at a shop follow Poisson.
In 15, an average of 4 customers arrive.

a)
A customer has just arrived. Then a minute passed and no one arrived. What is the probability of it takoing at least 5 more min. until another customer arrives?

b)
Consider 40 non-overlapping periods of 15 min.

What is the probability that
at least 7 and at most 15 of those intervals have at most 2 customers arriving?

In book, answer to
a) is 0.2636
b) is F(2.22) - F(-1.12) = 0.855

In a) although I don't see why, I understande that it's something about memorylessness or something. But how do you get to the answer in question b)?
 
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pinto89a said:
how do you get to the answer in question b)?

via binomial distribution
 
Ok, I see now.Thank you.
 
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