Wednesday
September 3, 2014

Homework Help: Statistics (Poisson)

Posted by Sean on Sunday, July 19, 2009 at 4:46pm.

Cars arrive at a toll booth according to a Poisson process with mean 80 cars per hour.

How long can the attendant's phone call last if the probability is at least .4 that no cars arrive during the call.

The book's answer is 23 seconds. That doesn't match mine and I was hoping to understand why...

p(y) = λ^y * e^-λ / y!
p(0) = e^-λ

p(0) > 0.4
e^-λ > 0.4
-λ > ln 0.4
λ < -ln 0.4

If x = call length (in seconds)
λ = x * 80 / 3600

x * 80/3600 < -ln 0.4
x < -3600/80 * ln 0.4
x < 41.2 seconds

Can anyone point out how to get 23 seconds or what I did wrong?

Answer this Question

First Name:
School Subject:
Answer:

Related Questions

math-probability - uppose that cars arrive at a traffic light according to a ...
statistics - A service station has a pump that distributes diesel fuel to ...
bus stats - John parks cars at a hotel. On the average, 6.0 cars will arrive in ...
math - automoniles arrive at the drive-through windom at a post office at the ...
Statistics - Suppose cars arrive at Burger King's drive-through at the rate of ...
Math/Statistics - STATISTICS PLEASE HELP!!!!! I am sorry this is jy second time ...
math - statistics - Football team makes in average 2 touchdowns per game. Use ...
Stastics - Suppose cars arrive at Burger King's drive-through at the rate of 20 ...
Statistics - The number of traffic accidents per day on a certain section of ...
Maths Probability - A dedicated professor has been holding infinitely long ...

Search
Members