Question

The university police department must write, on average, five tickets per day to keep department revenues at budgeted levels. Suppose the number of tickets written per day follows a Poisson distribution with a mean of 8.9. Find the probability that exactly four tickets are written on a randomly selected day.

Answer 1

0.1284

Explanation:

Answer 2

3.566%

Explanation:

The probability formula for a poisson distribution is:

`P( k )=(\lambda^(k)e^(-\lambda))/(k!) \\`

λ is the average of events

e is the euler's number

k is the number of events you want to know the probability

For this :

λ = 8.9 (on average the number of tickets is 8.9 per day)

k = 4 (you need to find the probability that exactly 4 tickets are written per day)

`P( k=4 )=(8.9^(4)e^(-8.9))/(4!)=0,03566 =3.566\%`