Nr of customers arriving at a shop follow Poisson.(adsbygoogle = window.adsbygoogle || []).push({});

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)?

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Poisson distribution

**Physics Forums | Science Articles, Homework Help, Discussion**