It is recommended to use a Poisson process to model the number of failures in commercial water pipes,

A research paper recommends using Poisson process to model the number of failures in commercial water pipes The paper also gives estimates the failure rate in units of failures per 100 miles of pipe per day; for four different types of pipe and for many different years_ For example, for cast iron pipe in 2005, the authors' estimate is the failure rate is 0.0864 failures per 100 miles per day: Suppose a town had 2500 miles of cast iron pipe underground in 2005 What is the probability of at least two failures

The correct answer will be d. -4

The answer that i got was 8/3